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2017 Spring Final Review PAP/GT Physics
Inverse Square Laws Ch 7 and Ch 16 mixMomentum and Collisions Ch 6Mechanical Energy Ch 5Heat/Thermo Ch 9 and Ch 10 mixWaves and Sound Ch 11 and Ch 12 mixLight and Reflection Ch 13Refraction, Interference, Diffraction Ch 14 and Ch 15 mixElectric Energy, Current, Power, and Circuits Ch 17 and Ch 18 mix
Section Quiz: Newton’s Law of Universal GravitationWrite the letter of the correct answer in the space provided.
__________ 1. What is the centripetal force that holds planets in orbit?a. inertiab. gravitational forcec. planetary forced. Kepler’s force
__________ 2. The force that Earth exerts on the moona. is greater than the force the moon exerts on Earth.b. is less than the force the moon exerts on Earth.c. is equal in magnitude to the force the moon exerts on Earth.d. causes tides.
__________ 3. How does the gravitational force between two objects change if the distance between the objects doubles?a. The force decreases by a factor of 4.b. The force decreases by a factor of 2.c. The force increases by a factor of 2.d. The force increases by a factor of 4.
__________ 4. What does G stand for?a. free-fall accelerationb. gravitational field strengthc. the constant of universal gravitationd. gravitational force
__________ 5. Which of the following is an expression of gravitational field strength?
a. c.
b. d.
__________ 6. Tides are caused bya. differences in the gravitational force of the moon at different points on Earth.b. differences in Earth’s gravitational field strength at different points on Earth’s surface.c. differences in the gravitational force of the sun at different points on Earth.d. fluctuations in the gravitational attraction between Earth and the sun.
__________ 7. When a person holds a ball above Earth’s surface, the system contains gravitational potential energy. Where is this potential energy stored?a. in the ballb. inside Earthc. in the person holding the balld. in the gravitational field between Earth and the ball
__________ 8. Evidence confirms that gravitational massa. depends on gravitational field strength.b. varies with location.c. depends on free-fall acceleration.d. equals inertial mass.
9. Explain why an astronaut weighs less on the moon than on Earth.___________________________________________________________________________________
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10.The moon has a mass of 7.35 1022 kg and a radius of 1.74 106 m. What is the gravitational force between the moon and an 85 kg astronaut? (G = 6.673 1011 Nm2/kg2)
7 Circular Motion and Gravitation
NEWTON’S LAW OF UNIVERSAL GRAVITATION
1. b
2. c
3. a
4. c
5. d
6. a
7. d
8. d
9. Weight is the product of mass and gravitational field strength. An astronaut weighs less on the moon than on Earth because
the gravitational field strength at the moon’s surface is less than the gravitational field strength on Earth’s surface.
10. 1.4 102 NGivenm1 = 7.35 1022 kgm2 = 85 kgr = 1.74 106 mG = 6.673 1011 Nm2/kg2
Solution
Section Quiz: Electric ChargeWrite the letter of the correct answer in the space provided.
__________ 1. Objects become electrically charged as a result of the transfer ofa. protons.b. electrons.c. neutrons.d. nuclei.
__________ 2. The nucleus of an atom has _______________ electric charge.a. a positiveb. a negativec. a neutrald. both positive or negative
__________ 3. Rubbing a balloon through dry hair gives the balloon a _______________ electric charge.a. positiveb. negative
c. neutrald. balanced
__________ 4. Robert Milliken’s research showed that electric charge is quantized, which means thata. a proton has a charge equal to that of two electrons.b. an electron can have any amount of electric charge.c. all charge is an integer multiple of a fundamental charge.d. all charge is an integer multiple of the charge of a neutron.
__________ 5. A student rubs a certain rod with plastic wrap. The rod then repels a glass rod that has been rubbed with silk and attracts a rubber rod that has been rubbed with fur. This observation shows that the first rod has a(n) _______________ charge.a. positiveb. negativec. neutrald. undetermined
__________ 6. A negatively charged rod is brought near a metal sphere that is not grounded. When the rod is taken away, the metal sphere will havea. a positive charge.b. a negative charge.c. an induced charge.d. no charge.
__________ 7. A conductor, such as a copper rod, can be charged by contact with another charged object only if the metal rod isa. an insulator.b. grounded to Earth.c. insulated from Earth.d. positively charged.
__________ 8. Uncharged objects can be attracted by a charged object because the uncharged objects acquire a surface charge by the process ofa. contact.b. polarization.c. conduction.d. charge transfer.
9. Electrons in conducting materials are loosely held by atoms in contrast to electrons in insulators, which tend to be tightly held. How does this fact explain the difference between electrical conductors and electrical insulators?___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
10.A grounded conductor may be charged by the process of _______________ when a charged object is brought near the conductor.___________________________________________________________________________________
1. b
2. a
3. b
4. c
5. a
6. d
7. c
8. b
9. The electrons in a conductor are free to move from place to place, whereas the electrons in insulators cannot move freely.
10. induction
Section Quiz: Electric ForceWrite the letter of the correct answer in the space provided.
__________ 1 An electric force F exists between two objects, both having the charge q. If the charge on one object is doubled to 2q, the force between the objects becomes
a. F c. 2F.
b. F d. 4F.
__________ 2. An electric force F exists between two objects separated from each other by distance r. If the distance is decreased to 0.5r, the force between the two objects becomes
a. F c. 2F
b. F d. 4F.
__________ 3. Two point charges, initially 2 cm apart, are moved to a distance of 8 cm apart. By what factor does the resulting electric force between them change?
a. 2 c.
b. 4 d.
__________ 4. Two charged objects are near each other. One has a charge of
a. 16 c. 2b. 4 d. No change occurs.
__________ 5. Electric force and gravitational force are alike in that both forcesa. depend on charge. c.act only when objects are
touching.b. depend on mass. d. are field forces.
__________ 6. The diagram above represents an array of point charges of the magnitudes shown. Assume that no net force acts on charge q3. What can you say about the sign and magnitude of charge q3?
a. The charge must be positive and less than the charge on q1 and q2.
b. The charge must be positive and the same as the charge on q1 and q2.
c. The charge must be negative and the same as the charge on q1 and q2.d. The charge can have any sign and any magnitude.
__________ 7. The diagram above represents an array of point charges of the magnitudes shown. Which of the following choices best represents the direction of the net electric force acting on charge q3?
__________ 8. Which of the following best represents a difference between electric force and gravitational force?
a. Gravitational force is stronger than electric force.b. Electric force can both attract and repel.c. Electric force is inversely proportional to the square of the distance between objects.d. Gravitational force exists between objects that are not touching.
9. The resultant force acting on a charged object placed near other charged objects is the _______________ sum of the of the individual forces acting on the object.___________________________________________________________________________________
10.Two point charges having charge values of 4.0 106 C and 8.0 106 C, respectively, are separated by 2.4 102 m. What is the value of the mutual force between them? (kc = 8.99 109 Nm2/C2)
ELECTRIC FORCE1. c
2. d
3. d
4. b
5. d
6. d
7. a
8. b
9. vector
10. 5.0 102 N
Givenq1 = 4.0 106 Cq2 = 8.0 106 Cr = 2.4 102 mkC = 8.99 109 Nm2/C2
Solution
Felectric = 5.0 102 N
Momentum and Collisions
Chapter Test BMULTIPLE CHOICEIn the space provided, write the letter of the term or phrase that best completes each statement or best answers each question.
__________ 1. Which of the following has the greatest momentum?a. a tortoise with a mass of 275 kg moving at a velocity of 0.55 m/sb. a hare with a mass of 2.7 kg moving at a velocity of 7.5 m/sc. a turtle with a mass of 91 kg moving at a velocity of 1.4 m/sd. a roadrunner with a mass of 1.8 kg moving at a velocity of 6.7 m/s
__________ 2. A person sitting in a chair with wheels stands up, causing the chair to roll backward across the floor. The momentum of the chaira. was zero while stationary and increased when the person stood.b. was greatest while the person sat in the chair.c. remained the same.d. was zero when the person got out of the chair and increased while the person sat.
__________ 3. A 0.2 kg baseball is pitched with a velocity of 40 m/s and is then batted to the pitcher with a velocity of 60 m/s. What is the magnitude of change in the ball’s momentum?a. 2 kgm/s c. 8 kgm/sb. 4 kgm/s d. 20 kgm/s
__________ 4. Which of the following statements properly relates the variables in the equation Ft = p?a. A large constant force changes an object’s momentum over a long time interval.b. A large constant force acting over a long time interval causes a large change in momentum.c. A large constant force changes an object’s momentum at various time intervals.d. A large constant force does not necessarily cause a change in an object’s momentum.
__________ 5. Two objects with different masses collide and bounce back after an elastic collision. Before the collision, the two objects were moving at velocities equal in magnitude but opposite in direction. After the collision,a. the less massive object had gained momentum.b. the more massive object had gained momentum.c. both objects had the same momentum.d. both objects lost momentum.
6.Two swimmers relax close together on air mattresses in a pool. One swimmer’s mass is 48 kg, and the other’s mass is 55 kg. If the swimmers push away from each other,
a. their total momentum triples.b. their momenta are equal but opposite.c. their total momentum doubles.d. their total momentum decreases.
__________ 7. Which of the following statements about the conservation of momentum is not correct?a. Momentum is conserved for a system of objects pushing away from each other.b. Momentum is not conserved for a system of objects in a head-on collision.c. Momentum is conserved when two or more interacting objects push away from each other.d. The total momentum of a system of interacting objects remains constant regardless of forces between the
objects.
__________ 8. Two balls of dough collide and stick together. Identify the type of collision.a. elastic c. inelasticb. perfectly elastic d. perfectly inelastic
__________ 9. Which of the following best describes the momentum of two bodies after a two-body collision if the kinetic energy of the system is conserved?a. must be less c. might also be conservedb. must also be conserved d. is doubled in value
SHORT ANSWER10.A baseball pitcher’s first pitch is a fastball, moving at high speed. The pitcher’s second pitch—with the same ball—is a
changeup, moving more slowly. Which pitch is harder for the catcher to stop? Explain your answer in terms of momentum.___________________________________________________________________________________
___________________________________________________________________________________
11.Is it possible for a spaceship traveling with constant velocity to experience a change in momentum? Explain your answer.___________________________________________________________________________________
___________________________________________________________________________________
12.Each croquet ball in a set has a mass of 0.50 kg. The green ball travels at10.5 m/s and strikes a stationary red ball. If the green ball stops moving, what is the final speed of the red ball after the collision?___________________________________________________________________________________
13.A moderate force will break an egg. Using the concepts of momentum, force, and time interval, explain why an egg is more likely to break when it is dropped on concrete than if it is dropped on grass.___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
14.Why is the sound produced by a collision evidence that the collision is not perfectly elastic?___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
PROBLEM15.What velocity must a 1340 kg car have in order to have the same momentum as a 2680 kg truck traveling at a velocity of 15
m/s to the west?
16.A 6.0 102 kg tennis ball moves at a velocity of 12 m/s. The ball is struck by a racket, causing it to rebound in the opposite direction at a speed of 18 m/s. What is the change in the ball’s momentum?
17.A train with a mass of 1.8 103 kg is moving at 15 m/s when the engineer applies the brakes. If the braking force is constant at 3.5 104 N, how long does it take the train to stop? How far does the train travel during this time?
18.An astronaut with a mass of 85 kg is outside a space capsule when the tether line breaks. To return to the capsule, the astronaut throws a 2.0 kg wrench away from the capsule at a speed of 14 m/s. At what speed does the astronaut move toward the capsule?
19.A 0.10 kg object makes an elastic head-on collision with a 0.15 kg stationary object. The final velocity of the 0.10 kg object after the collision is0.045 m/s, and the final velocity of the 0.15 kg object after the collision is 0.16 m/s. What was the initial velocity of the 0.10 kg object?
20.A 90 kg halfback runs north and is tackled by a 120 kg opponent running south at 4 m/s. The collision is perfectly inelastic. Just after the tackle, both players move at a velocity of 2 m/s north. Calculate the velocity of the 90 kg player just before the tackle.
1. aGiven
Solution
2. a
3. dGiven
Solutionp = m(vf vi) = (0.2 kg)(60 m/s 40 m/s) = 20 kgm/s
4. b
5. a
6. b
7. b
8. d
9. b
10. The first pitch is harder to stop. The first pitch has greater momentum because it has a greater velocity.
11.Yes, a spaceship traveling with constant velocity could experience a change in momentum if its mass changed, for example,
by burning fuel.
12. 10.5 m/s
13. Stopping a falling egg requires changing the momentum of the egg from its value at the time of first impact to zero. If the
egg hits the concrete, the time interval over which this happens is very small, so the force is large. If the egg lands on grass,
the time interval over which the momentum changes is larger, so the force on the egg is smaller.
14. Producing sound requires energy. Because the system of objects loses some energy as sound is produced in the collision,
the total kinetic energy cannot be conserved, so the collision cannot be perfectly elastic.
15. 30 m/s to the westGiven
Solution
16.Given
Solution
17.Given
Solution
18. 0.33 m/sGiven
Solution
19. 0.20 m/sGiven
Solution
20. 10 m/s to the north
Given
Solution
Work and Energy
Chapter Test BMULTIPLE CHOICEIn the space provided, write the letter of the term or phrase that best completes each statement or best answers each question.
__________ 1. If the sign of work is negative,a. the displacement is perpendicular to the force.b. the displacement is in the direction opposite the force.c. the displacement is in the same direction as the force.d. no work is done.
__________ 2. A child moving at constant velocity carries a 2 N ice-cream cone 1 m across a level surface. What is the net work done on the ice-cream cone?a. 0 J c. 2 Jb. 0.5 J d. 20 J
__________ 3. A worker does 25 J of work lifting a bucket, then sets the bucket back down in the same place. What is the total net work done on the bucket?a. 25 J c. 25 Jb. 0 J d. 50 J
__________ 4. If both the mass and the velocity of a ball were tripled, the kinetic energy of the ball would increase by a factor ofa. 3. c. 9.b. 6. d. 27.
__________ 5. What is the kinetic energy of a 0.135 kg baseball thrown at 40.0 m/s?a. 54.0 J c. 108 Jb. 87.0 J d. 216 J
__________ 6. If friction is the only force acting on an object during a given physical process, which of the following assumptions can be made in regard to the object’s kinetic energy?a. The kinetic energy decreases.b. The kinetic energy increases.c. The kinetic energy remains constant.d. The kinetic energy decreases and then increases.
__________ 7. The equation for determining gravitational potential energy isPEg = mgh. Which factor(s) in this equation is (are) not intrinsic to an object?a. m c. hb. g d. both g and h
__________ 8. Which of the following parameters does not depend on how resistant a spring is to being compressed or stretched?a. compression distance c. spring constantb. relaxed length d. stretching distance
__________ 9. What is the potential energy of a 1.0 kg mass 1.0 m above the ground?a. 1.0 J c. 10 Jb. 9.8 J d. 96 J
__________ 10. Why doesn’t the principle of mechanical energy conservation hold in situations when frictional forces are present?a. Kinetic energy is not completely converted to a form of potential energy.b. Potential energy is completely converted to a form of gravitational energy.c. Chemical energy is not completely converted to electrical energy.d. Kinetic energy is completely converted to a form of gravitational energy.
__________ 11. For which of the following situations is the conservation of mechanical energy most likely to be a valid assumption?a. A skateboard rolls across a sewer grate.b. A parachutist falls from a plane.c. You rub your hands together to keep warm.d. A soccer ball flies through the air.
__________ 12. A 3.00 kg toy falls from a height of 1.00 m. What will the kinetic energy of the toy be just before the toy hits the ground? (Assume no air resistance and that g = 9.81 m/s2.)a. 98.0 J c. 29.4 Jb. 0.98 J d. 294 J
__________ 13. What is the average power supplied by a 60.0 kg person running up a flight of stairs a vertical distance of 4.0 m in 4.2 s?a. 57 W c. 560 Wb. 240 W d. 670 W
SHORT ANSWER14.Explain the scientific meaning of work.
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
15.What form of energy is associated with the position of an object in Earth’s gravitational field?___________________________________________________________________________________
16.Describe the relationship between kinetic energy and gravitational potential energy during the free fall of a pencil from a desk.
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
17.Write an equation that expresses the conservation of mechanical energy in a system that involves kinetic energy, gravitational potential energy, and elastic potential energy.___________________________________________________________________________________
18.Show how the alternative definition of power can be derived by substituting the definitions of work and speed into the
standard definition of power, .
19.Which motor performs more work in the same amount of time—a 10 kW motor or a 20 kW motor? How much more work can it do?___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________PROBLEM20.What is the kinetic energy of a 1.5 103 kg car traveling at 25 m/s?
21.A worker pushes a box with a horizontal force of 50.0 N over a level distance of 5.0 m. If a frictional force of 43 N acts on the box in a direction opposite to that of the worker, what net work is done on the box ?
22.A professional skier starts from rest and reaches a speed of 56 m/s on a ski slope angled 30.0 above the horizontal. Using the work-kinetic energy theorem and disregarding friction, find the minimum distance along the slope the skier would have to travel in order to reach this speed.
23.An 80.0 kg climber climbs to the top of Mount Everest, which has a peak height of 8848 m. What is the climber’s potential energy with respect to sea level?
24.Old Faithful geyser in Yellowstone National Park shoots water every hour to a height of 40.0 m. With what velocity does the water leave the ground? (Assume no air resistance and that g = 9.81 m/s2.)
25.Water flows over a section of Niagara Falls at a rate of 1.20 106 kg/s and falls 50.0 m. What is the power of the waterfall?
1. b
2. a
3. b
4. d5. c
Solution
6. a
7. d
8. b
9. bSolution
10. a
11. d
12. cSolution
13. cSolution
14. Work, in the scientific sense, is the product of the component of a force along the direction of displacement and the
magnitude of the displacement. No work is done unless a force causes some displacement that is not perpendicular to the
force.
15. gravitational potential energy
16. At the top of the fall, all the energy is gravitational potential energy. During the fall, gravitational potential energy
decreases as it is transformed into kinetic energy. When the pencil reaches the ground, all the energy is kinetic energy.
17.
18. Definition of Power:
Definition of work:
Definition of speed
Alternative definition of power: 19.The 20 kW motor does twice as much work in the same amount of time.
20. 4.7 105 JGivenm = 1.5 × 103 kgv = 25 m/sSolution
21. 35 JGiven
Solution
22. 320 mGiven
Solution
23. 6.94 106 JGiven
Solution
24. 28.0 m/sGiven
Solution
25. 589 MW Given
Solution
Section Quiz: Temperature and Thermal EquilibriumWrite the letter of the correct answer in the space provided.
__________ 1. Which of the following is proportional to the average kinetic energy of particles in matter?a. heatb. temperaturec. thermal equilibriumd. internal energy
__________ 2. What is the energy due to both the random motions of a substance’s particles and the potential energy due to the bonds between those particles called?a. vibrational energyb. rotational energyc. translational energyd. internal energy
__________ 3. What is the type of kinetic energy associated with a molecule spinning about its center of mass called?a. vibrational energyb. rotational energyc. translational energyd. internal energy
__________ 4. Which of the following statements best describes a state of thermal equilibrium between two systems?a. Both systems have the same mass.b. Both systems have the save volume.c. Both systems have the same temperature.d. Both systems contain the same amount of internal energy.
__________ 5. Which of the following statements correctly describes what occurs to a substance that undergoes thermal expansion?a. As the temperature increases, the volume of the substance increases.b. As the temperature increases, the volume of the substance decreases.c. As the temperature increases, the density of the substance increases.d. As the temperature increases, the mass of the substance decreases.
Heat continued
__________ 6. The temperature of the air is measured as 235 K. What is this temperature equal to in degrees Celsius?a. 508Cb. 203Cc. 38Cd. 68C
__________ 7. How are the Celsius and Kelvin temperature scales similar?a. Both scales are based on the freezing and boiling points of water.b. Both scales are based on absolute zero.c. Neither scale has negative temperature values.d. The difference of one degree is the same for both scales.
__________ 8. Which temperature scale is used widely in science, and is applied to non-scientific uses throughout most of the world?a. Celsiusb. Rankinec. Fahrenheitd. Kelvin
9. Explain how the kinetic energy of molecules in water accounts for its temperature.___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
10.The temperature on a warm day is 309.7 K. Calculate the equivalent to this temperature on the Fahrenheit temperature scale.
TEMPERATURE AND THERMAL EQUILIBRIUM
1. b
2. d
3. b
4. c
5. a
6. cGivenT = 235 KSolutionTC = T 273.15 = (235 273.15)C
= 38C
7. d
8. a
9. Energy is added to a water molecule, causing its kinetic energy to increase. The kinetic energy can be distributed through
the molecule’s translational motion in all directions, through its rotational motion around its center of mass, and through
vibrational motion along the bonds between the oxygen and hydrogen atoms. As the motion of the molecule and other
molecules becomes greater, they convey more energy during collisions to other forms of matter, increasing their kinetic
energies. These increases in energy account for and are measured as increases in temperature.
10. 97.9 FGivenT = 309.7 KSolutionT = TC + 273.15TC = T 273.15
Section Quiz: Defining HeatWrite the letter of the correct answer in the space provided.
__________ 1. What term is defined as the energy transferred between objects with different temperatures?a. internal energyb. workc. heatd. thermal equilibrium
__________ 2. What must be true if energy is to be transferred as heat between two bodies in physical contact?a. The two bodies must have different volumes.b. The two bodies must be at different temperatures.c. The two bodies must have different masses.d. The two bodies must be in thermal equilibrium.
__________ 3. What occurs to the particles in a substance at low temperature when energy is transferred to the substance as heat?a. The average kinetic energy of the particles increases.b. The average kinetic energy of the particles remains constant.c. The average kinetic energy of the particles decreases.d. The average kinetic energy of the particles varies unpredictably.
__________ 4. If energy is transferred spontaneously as heat from a substance with a temperature of T1 to a substance with a temperature of T2, which of the following statements must be true?a. T1 < T2
b. T1 = T2
c. T1 > T2
d. More information is needed.
__________ 5. A container with a temperature of 37C is submerged in a bucket of water with a temperature of 15C. An identical container with a temperature of T1 is submerged in an identical bucket of water with a temperature of T2. If the amounts of energy transferred as heat between the containers and the water are the same in both cases, which of the following statements is true?a. T1 = 5C; T2 = 37Cb. T1 = 10C; T2 = 47Cc. T1 = 12C; T2 = 32Cd. T1 = 7C; T2 = 29C
Heat continued
__________ 6. What is the process by which energy is transferred by the motion of cold and hot matter?a. thermal conductionb. thermal insulationc. convectiond. radiation
__________ 7. Which of the following is not a good thermal insulator?a. ceramicb. ironc. fiberglassd. cork
__________ 8. An arrow strikes a target, causing an internal energy increase of 18 J. If the arrow is fired so that it enters the target at the same height above the ground as when it was fired, what is the arrow's initial kinetic energy?a. 0 Jb. 9 Jc. 18 Jd. 27 J
9. Describe how energy is transferred between two objects at different temperatures, and how they reach thermal equilibrium.___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
10.A stone with a mass of 0.450 kg is dropped from the edge of a cliff. When the stone strikes the ground, the internal energy of the stone and ground increase by 1770 J. If the stone is initially at rest when it is dropped, how high above the ground is the cliff? (g = 9.81 m/s2)
DEFINING HEAT1. c
2. b
3. a
4. c
5. d
GivenTC = 37CTw = 15CSolutionT = 37C 15C = 22C =29C 7C
6. c
7. b
8. c
GivenU = 18 J
Solution
PE = 0 J; KEf = 0 J;
PE + KE + U = 0 = KEi + U
KEi = U = 18 J9. Energy is transferred as heat from the particles with
higher kinetic energies, and thus higher temperature, to
particles with lower kinetic energies, and lower
temperature, through collisions. In most cases, energy
is given up from the particles with higher energies to
those with lower energies. Overall, this causes the
temperature of the object originally at higher
temperature to decrease, and the temperature of the
originally lower temperature object to increase. When
the average kinetic energies of particles in both objects
are the same, the amount of energy transferred from the
first object to the second is the same as the energy
transferred from the second object to the first. At this
point, no net energy is exchanged, and the objects have
the same temperatures. They are then in thermal
equilibrium.
10. 401 m
Given
U = 1770 J
m = 0.450 kg
g = 9.81 m/s2
Solution
PE + KE + U = 0
The kinetic energy increases with the decrease in potential energy, and then decreases with the increase in the internal energy of the water. Thus, the net change in kinetic energy is zero. Assuming final potential energy has a value of zero, the change in the internal energy equals:
0 PEi + U = 0
U = PEi = mgh
h=DUmg
=1770J( 0.450 kg)(9. 81m/s2 )
=
401 m
Vibrations and Waves
Chapter Test BMULTIPLE CHOICEIn the space provided, write the letter of the term or phrase that best completes each statement or best answers each question.
__________ 1. Vibration of an object about an equilibrium point is called simple harmonic motion when the restoring force is proportional toa. time. c. a spring constant.b. displacement. d. mass.
__________ 2. A mass-spring system can oscillate with simple harmonic motion because a compressed or stretched spring has what kind of energy?a. kinetic c. gravitational potentialb. mechanical d. elastic potential
__________ 3. A pendulum swings through a total of 28. If the displacement is equal on each side of the equilibrium position, what is the amplitude of this vibration? (Disregard frictional forces acting on the pendulum.)a. 28 c. 56b. 14 d. 7.0
__________ 4. If a pendulum is adjusted so that its frequency changes from 10 Hz to 20 Hz, its period will change from n seconds toa. n/4 seconds. c. 2n seconds.b. n/2 seconds. d. 4n seconds.
__________ 5. By what factor should the length of a simple pendulum be changed in order to triple the period of vibration?a. 3 c. 9b. 6 d. 27
__________ 6. Each stretched region in the waveform of the longitudinal wave shown on the right corresponds to what feature of the transverse wave below it?a. wavelengthb. crestsc. troughsd. amplitude
__________ 7. Suppose that two sound waves passing through the same medium have different wavelengths. Which of the following is most likely to be the reason for the differing wavelengths?a. the nature of the medium c. differences in frequencyb. differences in amplitude d. the type of wave
__________ 8. When a mechanical wave’s amplitude is reduced by half, the energy the wave carries in a given time interval isa. doubled. c. decreased to one-half.b. increased by a factor of 1.4. d. decreased to one-fourth.
__________ 9. Two waves traveling in opposite directions on a rope meet and undergo complete destructive interference. Which of the following best describes the waves a moment after the waves meet and coincide?a. The waves no longer exist.b. The waves continue unchanged.c. The waves reflect and travel backward.d. A single wave continues along the rope.
__________ 10. Which of the following types of interference will occur when the pulses in the figure above meet?a. no interference c. partial destructiveb. complete constructive d. complete destructive
__________ 11. Consider two identical wave pulses on a rope having a fixed end. Suppose the first pulse reaches the end of the rope, is reflected back, and then meets the second pulse. When the two pulses overlap exactly, what will be the amplitude of the resultant pulse?a. zerob. same as the original pulsesc. double the amplitude of the original pulsesd. half the amplitude of the original pulses
__________ 12. A 2.0 m long stretched rope is fixed at both ends. Which wavelength would not produce standing waves on this rope?a. 2.0 m c. 4.0 mb. 3.0 m d. 6.0 m
__________ 13. A 3.0 m long stretched string is fixed at both ends. If standing waves with a wavelength of two-thirds L are produced on this string, how many nodes will be formed?a. 0 c. 3b. 2 d. 4
SHORT ANSWER14.In an oscillating mass-spring system, the restoring force is a result of the force exerted by the spring. What causes the
restoring force in a swinging pendulum?___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
15.If a spring is stretched from a displacement of 10 cm to a displacement of 30 cm, the force exerted by the spring increases by a factor of ___________.___________________________________________________________________________________
16.In an old-fashioned pendulum clock, the bob is moved up and down to adjust the clock to keep accurate time. How would you adjust the bob in order to correct a clock that runs too fast? Explain why the adjustment works.___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
17.A boat produces a wave as it passes an aluminum can floating in a lake. Explain why the can is not moved along in the direction of wave motion.___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
18.What is the difference between a pulse wave and a periodic wave?___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
19.What feature of a wave increases when the source of vibration increases in energy?___________________________________________________________________________________
20.A standing wave is produced by plucking a string. The points along the plucked string that appear not to be vibrating are produced by _____________ interference.___________________________________________________________________________________
PROBLEM21.A mass on a spring that has been compressed 0.1 m has a restoring force of
20 N. What is the spring constant?
24.Radio waves from an FM station have a frequency of 103.1 MHz. If the waves travel with a speed of 3.00 108 ms, what is the wavelength?
25.Vibration of a certain frequency produces a standing wave on a stretched string that is 2.0 m long. The standing wave has 7 nodes and 5 antinodes. What is the wavelength of the wave that produces this standing wave?
Vibrations and Waves
CHAPTER TEST B (ADVANCED)
1. b2. d
3. b
4. b
5. c
6. c
7. c
8. d
9. b
10. c
11. a
12. b
13. d
14. The restoring force in a swinging pendulum is a component of the gravitational force acting on the pendulum bob.
15. three
16. Moving the pendulum bob down increases the length of the pendulum. As a result, the period of the pendulum increases
and the frequency decreases.
17. The water wave is a disturbance moving through the water, but the water (the medium) is not carried forward with the
wave.
18. A pulse wave is a single traveling disturbance resulting from a motion that is not repeated. A periodic wave is one whose
source is repeated motion.
19. The amplitude increases.
20. (complete) destructive
21. 200 N/mGiven
Solution
24. 2.91 mGiven
Solution
25. 0.80 mGivenL = 2.0 mThe standing wave has 5 antinodes, i.e.,5 loops.SolutionA single loop (antinode) is produced by a wavelength equal to 2L. Two loops (one complete wavelength) are produced by a wavelength of L. A wavelength of 2/3 L results in 3 antinodes. The following pattern emerges:
Sound Chapter Test B
MULTIPLE CHOICEIn the space provided, write the letter of the term or phrase that best completes each statement or best answers each question.
__________ 1. Of the following materials, sound waves travel fastest througha. helium at 0C. c. copper at 0C.b. air at 0C. d. air at 100C.
__________ 2. The point at which a ray crosses a wave front corresponds to a _____________ of a sound wave.a. wavelength c. troughb. compression d. source
__________ 3. A train moves down the track toward an observer. The sound from the train, as heard by the observer, is _______________ the sound heard by a passenger on the train.a. the same as c. higher in pitch thanb. a different timbre than d. lower in pitch than
__________ 4. If you are on a train, how will the pitch of the train’s whistle sound to you as the train moves?a. The pitch will become steadily higher.b. The pitch will become steadily lower.c. The pitch will not change.d. The pitch will become higher, and then become lower.
__________ 5. At a distance of 3 m, the intensity of a sound will be _____________ the intensity it was at a distance of 1 m.a. one-ninth c. 3 timesb. one-third d. 9 times
__________ 6. The intensity of a sound at any distance from the source is directly proportional to the sound’sa. wavelength. c. power.b. pitch. d. frequency.
__________ 7. If the intensity of a sound is increased by a factor of 100, the new decibel level will increasea. by two units. c. by a factor of 10.b. to twice the old one. d. by 20 units.
__________ 8. The Tacoma Narrows bridge collapsed in 1940 when winds caused ______________ to build up in the bridge.a. a compression wave c. a standing waveb. a longitudinal wave d. friction
__________ 9. For a standing wave in an air column in a pipe that is open at both ends, there must be at leasta. one node and one antinode.b. two nodes and one antinode.c. two antinodes and one node.
d. two nodes and two antinodes.
__________ 10. If a guitar string has a fundamental frequency of 500 Hz, what is the frequency of its second harmonic?a. 250 Hz c. 1000 Hzb. 750 Hz d. 2000 Hz
__________ 11. Musical instruments of different types playing the same note may often be identified by the ______________ of their sounds.a. pitch c. fundamental frequencyb. intensity d. timbre
__________ 12. How many beats per second are heard when two vibrating tuning forks having frequencies of 342 Hz and 345 Hz are held side by side?a. 687 Hz c. 5 Hzb. 343.5 Hz d. 3 Hz
__________
13._In the figure shown above, a beat occurs ata. t1. c. t3.b. t2. d. t1 and t3.
SHORT ANSWER14.Unlike a transverse wave on a rope, sound travels as a(n) ___________ wave.
___________________________________________________________________________________
15.Each trough of a sine wave used to represent a sound wave corresponds to a(n) _______________ of the sound wave.___________________________________________________________________________________
16.What happens to pitch when the frequency of a sound wave increases?___________________________________________________________________________________
17.Under what conditions can a spherical wave front be regarded as a plane wave front? Explain.___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
18.Describe any changes in pitch of the sound a stationary observer hears from the siren of an ambulance as the ambulance passes the observer.___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
19.What happens to the intensity of a sound as the distance from the source increases from 10 m to 20 m? Explain.___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
20.Suppose you play a music CD in a room where there is a piano. During the silence between songs, you hear a musical note coming from the piano, but no one has touched the piano. Explain your observation.___________________________________________________________________________________
___________________________________________________________________________________
21.It is possible for a highly amplified musical note to cause a crystal goblet to shatter. Explain how this might occur.___________________________________________________________________________________
___________________________________________________________________________________
PROBLEM22.What is the intensity of sound waves produced by a trumpet at a distance of 1.6 m when the power output of the trumpet is
0.30 W?
25.As two notes are sounded, 6 beats per second are heard. The frequency of one note is 571 Hz. What is the frequency of the other note?
Sound
CHAPTER TEST B (ADVANCED)1. c2. b
3. c
4. c
5. a
6. c
7. d
8. c
9. c
10. c
11. d
12. d
13. b
14. longitudinal
15. rarefaction
16. The pitch rises.
17. As a sphere increases in radius, sections of its surface
approach a plane surface. A plane wave is a section of a
spherical wave that has such a large radius that sections
of it appear planar. This condition appears when the
observer of the wave is at a large distance from the
source.
18. The apparent pitch of the sound drops as the ambulance
passes.
19. The distance from the source doubles, so the intensity
decreases to one-fourth of its value at the 10 m
distance. The intensity is inversely proportional to the
square of the distance from the source, or intensity
1/r2.
20. One of the musical sounds from the CD matches the
natural frequency of the string in the piano. As a result,
the energy of the sound wave causes the string to
vibrate in resonance with the note from the CD.
21. If the musical note is at the fundamental frequency of
the glass, the glass will absorb energy from the sound
waves and vibrate in resonance with the note. If the
sound is loud enough, the vibration will overcome the
strength of the glass and the goblet will shatter.
22.GivenP = 0.30 W
r = 1.6 mSolution
25. 565 Hz or 577 HzGiven
Solution
Light and Reflection
Chapter Test BMULTIPLE CHOICEIn the space provided, write the letter of the term or phrase that best completes each statement or best answers each question.
__________ 1. What is the wavelength of microwaves of 3.0 109 Hz frequency?a. 0.050 m c. 0.10 mb. 0.060 m d. 0.20 m
__________ 2. What is the frequency of an electromagnetic wave with a wavelength of 1.0 105 m?a. 1.0 1013 Hz c. 3.0 1013 Hzb. 3.0 103 Hz d. 1.0 103 Hz
__________ 3. When red light is compared with violet light,a. both have the same frequency.b. both have the same wavelength.c. both travel at the same speed.d. red light travels faster than violet light.
__________ 4. The relationship between frequency, wavelength, and speed holds for light waves becausea. light travels slower in a vacuum than in air.b. all forms of electromagnetic radiation travel at a single speed in a vacuum.c. light travels in straight lines.d. different forms of electromagnetic radiation travel at different speeds.
__________ 5. If you are reading a book and you move twice as far away from the light source, how does the brightness at the new distance compare with that at the old distance? It isa. one-eighth as bright. c. one-half as bright.b. one-fourth as bright. d. twice as bright.
__________ 6. Snow reflects almost all of the light incident upon it. However, a single beam of light is not reflected in the form of parallel rays. This is an example of _______________ reflection off a _______________ surface.a. regular, rough c. diffuse, specularb. regular, specular d. diffuse, rough
Chapter Test B continued
__________ 7. When incoming rays of light strike a flat mirror at an angle close to the surface of the mirror, the reflected rays area. inclined high above the mirror’s surface.b. parallel to the mirror’s surface.c. perpendicular to the mirror’s surface.d. close to the mirror’s surface.
__________ 8. If a light ray strikes a flat mirror at an angle of 29 from the normal, the reflected ray will bea. 29 from the normal. c. 29 from the mirror’s surface.b. 27 from the normal. d. 61 from the normal.
__________ 9. When two parallel mirrors are placed so that their reflective sides face each other, _______________ images form. This is because the image in one mirror becomes the _______________ for the other mirror.a. multiple, object c. inverted, center of curvatureb. reduced, virtual image d. enlarged, focal point
__________ 10. A concave mirror with a focal length of 10.0 cm creates a real image 30.0 cm away on its principal axis. How far from the mirror is the corresponding object?a. 20 cm c. 7.5 cmb. 15 cm d. 5.0 cm
__________ 11. In the diagram shown above, the image of object B would bea. virtual, enlarged, and inverted.b. real, enlarged, and upright.c. virtual, reduced, and upright.d. virtual, enlarged, and upright.
Chapter Test B continued
__________ 12. In the diagram shown above, the image of object B would bea. real, reduced, and upright.b. virtual, enlarged, and upright.c. virtual, reduced, and inverted.d. virtual, reduced, and upright.
__________ 13. When parallel rays that are also parallel to the principal axis strike a spherical mirror, rays that strike the mirror _______________ the principal axis are focused at the focal point. Those rays that strike the mirror _______________ the principal axis are focused at points between the mirror and the focal point.a. perpendicular to, far fromb. close to, perpendicular to
c. close to, far fromd. far from, close to
__________ 14. If you looked at a light through the lenses from two polarizingsunglasses that were overlapped at right angles to each other,a. all of the light would pass through.b. most of the light would pass through.c. little of the light would pass through.d. none of the light would pass through.
SHORT ANSWER15. Why is the ultraviolet portion of the electromagnetic spectrum, not the microwave or infrared red portion, used to sterilize
medical instruments?___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
16.The electromagnetic spectrum is continuous and there is no sharp division between one kind of wave and the next. Assuming that the preceding statement is true, how do physicists distinguish one type of electromagnetic wave from another?___________________________________________________________________________________
___________________________________________________________________________________
17. How are the terms luminous flux and illuminance related to each other?___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
18. If a light ray strikes a flat mirror with an angle of incidence equal to 52, what is the angle of reflection? Explain.___________________________________________________________________________________
___________________________________________________________________________________
CHAPTER TEST B (ADVANCED)1. c
Given
Solution
Rearrange the wave speed equation, to isolate and calculate.
2. bGiven
Solution
Rearrange the wave speed equation, to isolate f, and calculate.
3. c
4. b
5. b
6. d
7. d
8. a
9. a
10. bGivenf =10 . 0 cmq=30 . 0 cmSolutionRearrange the mirror equation,1p +1
q =1f , and solve for p .
1p=1
f−1
q=1
10 . 0 cm−1
30 . 0 cm=
330.0 cm
−130. 0 cm
=230 . 0 cm
p=15 cm 11. d
12. d
13. c
14. d
15. The ultraviolet portion of the electromagnetic spectrum is made of sufficiently high frequency (i.e., high energy)
electromagnetic radiation that can destroy bacteria or other pathogens.
16. Electromagnetic waves are distinguished by their different frequencies and wavelengths.
17. Luminous flux is a measure of the amount of light emitted from a light source. It is measured in lumens. Illuminance is a
derived unit that indicates the relationship between luminous flux and the distance from the light source squared.
Illuminance is the ratio of lumens/m2.
18. 52; According to the law of reflection, the angle of incidence is equal to the angle of reflection.
Refraction
Chapter Test BMULTIPLE CHOICEIn the space provided, write the letter of the term or phrase that best completes each statement or best answers each question.
__________ 1. Which is an example of refraction?a. A parabolic mirror in a headlight focuses light into a beam.b. A fish appears closer to the surface of the water than it really is when observed from a riverbank.c. In a mirror, when you lift your right arm, the left arm of your image is raised.d. Light is bent slightly around corners.
__________ 2. The _______________ of light can change when light is refracted because the velocity changes.a. frequency c. wavelengthb. medium d. transparency
__________ 3. When a light ray moves from air into glass, which has a higher index of refraction, its path isa. bent toward the normal.b. bent away from the normal.c. parallel to the normal.d. not bent.
__________ 4. When a light ray passes from water (n 1.333) into diamond(n 2.419) at an angle of 45, its path isa. bent toward the normal.b. bent away from the normal.c. parallel to the normal.d. not bent.
__________ 5. When a light ray passes from zircon (n 1.923) into fluorite(n = 1.434) at an angle of 60, its path isa. bent toward the normal. c. parallel to the normal.b. bent away from the normal. d. not bent.
__________
__________ 7. All of the following images can be formed by a converging lens except which one?a. virtual, upright, and magnifiedb. real and pointc. real, inverted, and magnifiedd. real, upright, and magnified
__________
__________ 10. If atmospheric refraction did not occur, how would the apparent time of sunrise and sunset be changed?a. Both would be later.b. Both would be earlier.c. Sunrise would be later, and sunset would be earlier.d. Sunrise would be earlier, and sunset would be later.
SHORT ANSWER11.What type of situation will produce the largest amount of bending when a light ray crosses the boundary between two
transparent media?___________________________________________________________________________________
___________________________________________________________________________________
12.How are two converging lenses used to view an object in a compound microscope?___________________________________________________________________________________
___________________________________________________________________________________
13.Why is it impossible to see an atom with a compound microscope?___________________________________________________________________________________
___________________________________________________________________________________
14.No refraction occurs when a light ray that is parallel to the normal strikes a transparent medium. Use the wave model of light to explain why.___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
15.What is the position and kind of image produced by the lens shown below? Draw a ray diagram to support your answer.___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
18.What is dispersion?___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
Refraction
CHAPTER TEST B (ADVANCED)1. b
2. c
3. a
4. a
5. b
7. d
10. c
11. when the difference between the substances’ indices of refraction is the greatest
12. An object placed just outside the focal length of the objective lens forms a real, inverted image just inside the focal point of
the eyepiece. This eyepiece, the second lens, serves to magnify the image.
13.In order to be seen, the object under a microscope must be at least as large as a wavelength of light. An atom is many times
smaller than a wavelength of visible light.
14. A light ray represents the direction of propagation of a planar wave front, which is the superposition of all the spherical
wave fronts. As these wave fronts enter a transparent medium, all of them strike the surface simultaneously and experience
a similar change in velocity at the same instant.
Although this results in a change in the overall wavelength of the spherical wave fronts, there is no change in the direction
of the wave fronts relative to each other. Therefore, no refraction occurs.
15. A real, inverted image that is smaller than the object will form between F and 2F.
18. Dispersion is the process of separating polychromatic light into its component wavelengths because n is a function of
wavelength for all material mediums.
Snell’s law states that the angles of refraction will be different for different wavelengths even if the angles of incidence are
the same.
WS 8: Ch 15 section 2 Diffraction (p. 526 – 533)
1. The bending of a wave when encountering an obstacle, opening, or edge is called ________________________.
2. An interference pattern, like the one produced with double slit interference, is produced when light passes through a single narrow slit. This is called a _________________________ pattern, and is evidence of light interfering with itself. In order to understand this phenomena, we invoke __________________________ principle, which states that a single slit can be viewed as a source of multiple point sources (wavelets) of light. In other words, light from ________ portion of the slit can interfere with light from _________________ portion of the slit.
3. Diffraction becomes more evident as the width of the slit is ________________________.
4. In diffraction, longer waves tend to bend ________________(more/less) than shorter waves.For this reason, ___________________ waves are best suited for communication around buildings and mountains.
5. Diffraction is the reason why the edges of shadows ___________(are/aren’t) sharp.
6. Diffraction gratings are used inside ______________________ to disperse white light in order to see characteristic wavelengths that are unique to each ____________________.
Section Quiz: Current and ResistanceWrite the letter of the correct answer in the space provided.
__________ 1. Electric current in a wire is thea. number of electric charges moving from one location to another in the wire.b. net movement of electrical energy through the wire.c. rate at which electric charges move through an area of the wire.d. rate at which electrical energy is used to move charges through the wire.
__________ 2. One ampere of current is the movement of ______________ through a given area in one second.a. one coulomb of chargeb. one volt of potential differencec. one joule of energyd. one electron
__________ 3. The diagram above represents a wire in which the net flow of electrons is to the right. The direction of the conventional current in the wirea. depends on the potential difference.b. is to the left.c. is the same direction as the electron flow.d. cannot be determined.
__________ 4. The speed at which an electron moves in an electric field in a conductor is thea. speed of light.b. average collision speed.c. drift velocity.
d. average electron speed.
__________ 5. When a current moves through a copper conductor, electrons collide with copper atoms. The result of these collisions isa. an increase in voltage.b. a decrease in resistance.c. an increase in temperature.d. a decrease in voltage.
__________ 6. What is the potential difference across a 10 resistor if the current in the resistor is 3.0 A?a. 0.3 Vb. 3 Vc. 30 Vd. 15 A
__________ 7. The current of a non-ohmic material is plotted against the applied potential. How would you describe the resulting graph?a. The graph will have a constant positive slope.b. The graph will have a variable positive slope.c. The graph will have a variable negative slope.d. The graph will have a constant negative slope.
__________ 8. Which factor is least likely to affect the resistance of a conductor?a. the length of the conductorb. the temperature of the conductorc. the overall shape of the conductord. the material the conductor is made from
9. When a light switch is turned on, the light comes on almost instantly. Why does the light come on so quickly if the drift velocity of the electrons in the wires is very small?___________________________________________________________________________________
___________________________________________________________________________________
10.A current of 295 A passes through an automobile starter motor. How long does the starter motor operate if 377 coulombs pass through the starter?
CURRENT AND RESISTANCE1. c
2. a
3. b
4. c
5. c
6. c
7. b
8. c
9. The electric field that provides the energy for the light moves at nearly the speed of light.
10. 1.28 sGivenI = 295 Aq = 377 C
Solution
Section Quiz: Electric PowerWrite the letter of the correct answer in the space provided.
__________ 1. A generator converts ______________ energy into electrical energy.a. chemicalb. mechanicalc. kineticd. potential
__________ 2. Electrical current in which there is no net motion of the charge carriers isa. direct current.b. alternating current.c. static current.d. static electricity.
__________ 3. In alternating current, the charge carriers movea. in all directions.b. in only one direction.c. repeatedly in one direction then in the opposite direction.d. from a lower to a higher electric potential.
__________ 4. Electrical appliances have labels that state the power used by the appliance. What does the power rating listed on the label represent?a. the amount of current the appliance usesb. the amount of electrical energy converted to heat or light by the appliancec. how quickly the appliance heats upd. the amount of energy converted each second into other forms of energy
__________ 5. Electric power is the rate at which charge carriersa. pass through an area.b. do work.c. move through a potential difference.d. collide with atoms.
__________ 6. The phenomenon called I2R loss is also known asa. joule heating.b. resistance.c. ohmic energy.d. alternating current loss.
__________ 7. Which statement is correct regarding electric power?a. Electric power equals current times resistance.b. Electric power equals the amount of electrical energy used by a device.c. Electric power equals the current times potential difference.d. Electric power equals the amount of electrical energy converted to other forms of energy.
__________ 8. A certain circuit connected to a 1.5 V battery dissipates 2.0 W of power. If a second battery is added to the circuit, resulting in a potential difference of 3.0 V, what power will be dissipated? Assume that the resistance of the circuit does not change.a. 0.50 Wb. 1.0 Wc. 2.0 Wd. 4.0 W
9. Explain how alternating current can deliver energy to a motor without any net flow of electrons through the motor.___________________________________________________________________________________
___________________________________________________________________________________
10.A microwave oven connected to a 117 V outlet operates at a current of 8.7 A. If the microwave oven is operated exactly 1 hour each day for 28 days, what is the cost of operating this microwave oven if the cost of electric energy is $0.115 per kWh?
1. b
2. b
3. c
4. d
5. b
6. a
7. c
8. d
9. With alternating current, electrons vibrate back and forth instead of flowing in one direction.
The energy of this vibration does useful work.
10. $3.2GivenV = 117 VI = 8.7 At = 28 hEnergy Cost = $0.115 per kWh
Circuits and Circuit Elements
Chapter Test AMULTIPLE CHOICEIn the space provided, write the letter of the term or phrase that best completes each statement or best answers each question.
__________ 1. Which of the following is the best description of a schematic diagram?a. uses pictures to represent the parts of a circuitb. determines the location of the parts of a circuitc. shows the parts of a circuit and how the parts connect to each otherd. shows some of the parts that make up a circuit
__________ 2. A circuit has a continuous path through which charge can flow from a voltage source to a device that uses electrical energy. What is the name of this type of circuit?a. a short circuit c. an open circuitb. a closed circuit d. a circuit schematic
__________ 3. How does the potential difference across the bulb in a flashlight compare with the terminal voltage of the batteries used to power the flashlight?a. The potential difference is greater than the terminal voltage.b. The potential difference is less than the terminal voltage.c. The potential difference is equal to the terminal voltage.d. It cannot be determined unless the internal resistance of the batteries is known.
__________ 4. Three resistors connected in series carry currents labeled I1, I2, and I3, respectively. Which of the following expresses the total current, It, in the system made up of the three resistors in series?a. It I1 + I2 + I3 c. It I1 I2 I3
b. d.
__________ 5. Three resistors connected in series have potential differences across them labeled V1, V2, and V3. Which of the following expresses the potential difference taken over the three resistors together?a. Vt V1 V2 V3
b.c. Vt V1 V2 V3
d.
__________ 6. Three resistors with values of R1, R2, and R3 are connected in series. Which of the following expresses the total resistance, Req, of the three resistors?
a. Req R1 R2 R3 c. Req R1 R2 R3
b. d.
__________ 7. Three resistors connected in parallel carry currents labeled I1, I2, and I3. Which of the following expresses the total current It in the combined system?a. It = I1 I2 I3 c. It I1 I2 I3
b. d.
__________ 8. Three resistors connected in parallel have potential differences across them labeled V1, V2, and V3. Which of the following expresses the potential difference across all three resistors?a. Vt = V1 V2 V3 c. Vt V1 V2 V3
b. d.
__________ 9. Three resistors with values of R1, R2, and R3 are connected in parallel. Which of the following expresses the total resistance, Req, of the three resistors?a. Req R1 R2 R3 c. Req R1 R2 R3
b. d.
__________ 10. Three resistors with values of 3.0 , 6.0 , and 12 are connected in parallel. What is the equivalent resistance of this combination?a. 0.26 c. 9.0 b. 1.7 d. 33
__________ 11. The equivalent resistance of a complex circuit is usually determined bya. inspection.b. simplifying the circuit into groups of series and parallel circuits.c. adding and subtracting individual resistances.d. dividing the sum of the individual resistances by the number of resistances.
__________ 12. To find the current in a complex circuit, it is necessary to know thea. potential difference in each device in the circuit.b. current in each device in the circuit.c. equivalent resistance of the circuit.d. number of branches in the circuit.
__________ 13. Two resistors with values of 6.0 and 12 are connected in parallel. This combination is connected in series with a 4.0 resistor. What is the equivalent resistance of this combination?a. 0.50 c. 8.0 b. 2.0 d. 22
__________ 14. What is the equivalent resistance for the resistors in the figure shown above?a. 1.3 c. 3.0 b. 2.2 d. 0.75
__________ 15. In any complex resistance circuit, the voltage across any resistor in the circuit is alwaysa. less than the voltage source.
b. equal to or less than the voltage source.c. equal to the voltage source.d. greater than the voltage source.
SHORT ANSWER
16. Identify the types of elements in the schematic diagram above and the number of each type.
___________________________________________________________________________________
___________________________________________________________________________________
17.Which bulb or bulbs will have a current in the schematic diagram shown on the right?_______________________________________________
___________________________________________________________________________________
18.Why does the potential difference measured at the terminals of a battery decrease as the amount of current supplied to a load increases?___________________________________________________________________________________
___________________________________________________________________________________
PROBLEM19.A current of 0.20 A passes through a 3.0 resistor. The resistor is connected in series with a 6.0 V battery and an unknown
resistor. What is the resistance value of the unknown resistor?
20.Three resistors with values of 27 , 81 , 16 , respectively, are connected in parallel. What is their equivalent resistance?
CHAPTER TEST A (GENERAL)1. c
2. b
3. c
4. c
5. a
6. a
7. a
8. c
9. d
10. bGivenR1 = 3.0 R2 = 6.0 R3 = 12 Solution
11. b
12. c
13. cGivenR1 = 6.0 R2 = 12 R3 = 4.0 Solution
14. bGiven
Solution
15.b
16. two batteries, three resistors
17. Bulb A has a current, but B and C do not because the switch is open.
18. A battery has a small internal resistance. As the current increases, the potential difference across this internal resistance
increases and reduces the potential difference measured at the terminals of the battery.
19. 27 Given
Solution
20.9.0
Given
Solution
21.Use Kirchhoff’s Rules to solve for the
Step 1 of the branch current method has already been done. The currents have been labeled in each branch of the circuit, and the directions are shown with arrows. Again, you don't have to be sure of these directions at this point. Simply choose directions, and if any of the currents come out to have negative signs, all it means is that the direction of that current is opposite to the way you've shown on your diagram.
Applying step 2 of the branch current method means looking at the junctions, and writing down a current equation. At junction a, the total current coming in to the junction equals the total current flowing away. This gives:
at junction a : I1 = I2 + I3
If we applied the junction rule at junction b, we'd get the same equation. So, applying the junction rule at one of the junctions is all we need to do. In some cases you will need to get equations from more than one junction, but you'll never need to get an equation for every junction.
There are three unknowns, the three currents, so we need to have three equations. One came from the junction rule; the other two come from going to step 3 and applying the loop rule. There are three loops to use in this circuit: the inside loop on the left, the inside loop on the right, and the loop that goes all the way around the outside. We just need to write down loop equations until each branch has been used at least once, though, so using any two of the three loops in this case is sufficient.
When applying the loop equation, the first step is to choose a starting point on one loop. Then walk around the loop, in either direction, and write down the change in potential when you go through a battery or resistor. When the potential increases, the change is positive; when the potential decreases, the change is negative. When you get back to your starting point, add up all the potential changes and set this sum equal to zero, because the net change should be zero when you get back to where you started.
When you pass through a battery from minus to plus, that's a positive change in potential, equal to the emf of the battery. If you go through from plus to minus, the change in potential is equal to minus the emf of the battery.
Current flows from high to low potential through a resistor. If you pass through a resistor in the same direction as the current, the potential, given by IR, will decrease, so it will have a minus sign. If you go through a resistor opposite to the direction of the current, you're going from lower to higher potential, and the IR change in potential has a plus sign.
Keeping all this in mind, let's write down the loop equation for the inside loop on the left side. Picking a starting point as the bottom left corner, and moving clockwise around the loop gives:
Make sure you match the current to the resistor; there is one current for each branch, and a loop has at least two branches in it.
The inner loop on the right side can be used to get the second loop equation. Starting in the bottom right corner and going counter-clockwise gives:
Plugging in the values for the resistances and battery emf's gives, for the three equations:
The simplest way to solve this is to look at which variable shows up in both loop equations (equations 2 and 3), solve for that variable in equation 1, and substitute it in in equations 2 and 3.
Rearranging equation 1 gives:
Substituting this into equation 2 gives:
Making the same substitution into equation 3 gives:
This set of two equations in two unknowns can be reduced to one equation in one unknown by multiplying equation 4 by 5 (the number 5, not equation 5!) and adding the result to equation 5.
Substituting this into equation 5 gives:
I2 = ( -4 + 1.5 ) / 5 = -0.5 A
The negative sign means that the current is 0.5 A in the direction opposite to that shown on the diagram. Solving for the current in the middle branch from equation 1 gives:
I3 = 1.5 - (-0.5) = 2.0 A
Solve for all blanks.
Solve for Req