liu po shan memorial college (2010-11)

PHYS / S5 / 2010-11 / First Term Exam /

S.5 1st Exam PHY

LIU PO SHAN MEMORIAL COLLEGE

(2010-11)

FIRST TERM EXAMINATION

PHYSICS Secondary FIVE

Date: 13-1-2010 (Thu)

Time: 2 hours

Question-Answer Book This paper must be answered in English.

1 Write your Name, Class and Class number in the spaces

provided on the this cover. 2 This paper consists of TWO sections, Section A and

Section B. Section A carries 50 marks and Section B carries 80 marks.

3 Answer ALL questions in each section. Write your

answers of both Sections in the spaces provided in this Question-Answer Book.

4 Unless otherwise specified, numerical answers should

be either exact or correct to 3 significant figures. 5 The last two pages of this Question-Answer Book

contains a list of data, formulae and relationships which you may find useful.

Name

Class

Class number

Teacher's Use Only

Section B Question No. Marks

1

2

3

4

5

6

7

8

9

10

11

Section B Total

Section A Total ____ × 2 = ______

Total marks

PHY / S5 / 2010-11 / First Term Exam /

Section A M.C. Questions (50 marks)

Do not write in this margin 1. There are 25 multiple choice questions in this section. Each question carries 2 marks.

2. ANSWER ALL QUESTIONS.

3. You should write down all your answers in the box at the end of each question on this Question-Answer Book.

4. You should write down only ONE answer for each question. If you give more than one answer, you will receive NO MARKS for that question.

5. No marks will be deducted for wrong answers. 1. The solid curve in the figure above shows a transverse wave at a certain instant.

After 0.2 s, the wave has travelled to the position indicated by the dashed curve. What are the wavelength and frequency of the wave?

Wavelength / cm Frequency / Hz

A. 1 2.5 B. 1 5 C. 2 1.25 D. 2 5

2. The diagram above shows a stationary wave produced by a vibrator. At a certain

instant, P is moving downward. What are the directions of motion of Q and R at that instant?

Q R A. upward upward B. upward downward C. downward upward D. downward downward

3.

Do not write in this margin

In a Young’s double-slit experiment, light of wavelength 600 nm is used. The

path difference between the light from the two slits X and Y to a point P on the screen is 3300 nm. O is equi-distant from X and Y. Which of the following is/are correct?

(1) P is a dark fringe. (2) Including P and O, there are six dark fringes between P and O. (3) The fringe separation on the screen increases if the light source is moved closer to the slits.

A. (1) only


B. (3) only C. (1) and (2) only D. (2) and (3) only

4. The figure above shows the circular wavefronts produced by two identical point

vibrators, S1 and S2, in a ripple tank. The solid lines represent crests. Which of the following correctly states the type of interference (constructive, destructive or neither) occuring at P, Q and R?

P Q R

A. neither destructive constructive B. constructive destructive constructive C. neither constructive destructive D. constructive constructive constructive



5. Which of the following statements about ultraviolet radiation is/are correct? (1) Ultraviolet radiation travels faster than ultrasound. (2) Ultraviolet radiation has a longer wavelength than infrared radiation. (3) Ultraviolet radiation has a smaller degree of diffraction than violet light

when pass through narrow slit.

A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

6. When a sound wave traveling in air enters into water, which of the following

statements is correct? A. The wavelength decreases and the speed increases. B. The wavelength increases and the speed decreases. C. Both the wavelength and the speed decrease. D. Both the wavelength and the speed increase. 7.

Note X Note Y Note Z

Musical notes X, Y and Z are shown on a CRO as above. The settings of the CRO are kept the same. Which of the musical notes has the highest pitch and which has the largest loudness? Highest pitch Largest loudness A. note Z note X B. note X note Y C. note X note Z D. note Y note Z


8.


Three uncharged metal spheres A, B and C are placed on insulating stands respectively. Spheres A and B are in contact while sphere C is placed at a small distance from sphere B as shown in the figure above. A negatively charged rod is brought near sphere A and sphere C is touched momentarily at the right. If the charged rod is held at the same position, which of the following correctly shows the charges carried by spheres A, B and C?

Sphere A Sphere B Sphere C A. positive negative zero B. positive negative negative C. positive negative positive D. zero zero positive

9. An electric field is shown above. P, Q and R are three points in the field. Which

of the following statements is/are correct? (1) When a positive charge is placed at P, its acceleration points towards Q. (2) When a charge is placed at R, the electric force exerted on it is zero. (3) The electric force exerted on a charge placed at P is larger than that at Q. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only



10. Which of the following statements about an electric field strength are correct? (1) Electric field strength is a vector. (2) The electric field strength is zero at all points where the electric potential is

zero.

(3) The electric field strength due to a point charge varies as 2r1 where r is the

distance from the charge.

A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

11.

Three point charges A, B and C are fixed at the vertices of a square and their signs and magnitudes are shown in the figure above. If a point charge P is placed at the remaining vertex of the square, it is in equilibrium. Which of the following statements is/are correct?

(1) The sign of point charge P cannot be determined. (2) Magnitude q1 must be equal to magnitude q2. (3) If the positions of point charge B and point charge C are exchanged, point

charge P will remain in equilibrium at the vertex.




12.

The diagram above shows a uniform electric field in which the equipotential lines are spaced 5.0 cm apart. What is the value of electric force exerted on a charge of +2.0 μC when placed in the field?

A. 1.2 × 10-2 N B. 2.4 × 10-2 N C. 1.2 × 104 N D. 2.4 × 104 N

13.

In the circuit shown above, the e.m.f. of the battery is V and the ratio of the resistance of R1 to R2 to R3 is 1 : 2 : 3. What is the potential difference across R1?

A. 6V

B. 3V

C. 2V

D. 3

2V


14.


In the figure shown above, the circuit consists of four identical bulbs. If switch S

is closed, which bulb(s) will become brighter? A. 3 only B. 1 and 2 only

6 V

V1 V2

1 Ω 2 Ω

C. 3 and 4 only D. 1, 2 and 4 only

15.

In the circuit shown above, what are the readings of the voltmeters when the switch is (i) closed and is (ii) opened respectively?

(i) switch closed (ii) switch opened V1 V2 V1 V2

A. 2 V 4 V 0 V 6 V B. 2 V 4 V 6 V 0 V C. 1 V 3 V 0 V 6 V D. 1 V 3 V 6 V 0 V



16.

A 9 V battery, an ammeter and an eureka wire of resistance 100 Ω are connected into a circuit as shown above. The sliding contact is located at the mid-point of the eureka wire. If the reading of the ammeter is 0.17 A, what is the internal resistance of the battery?

A. 0.29 Ω B. 2.94 Ω C. 5.29 Ω D. 52.9 Ω

17.

Henry wants to use an ammeter and a voltmeter to measure the resistance of a light bulb. He connects the circuit as shown above. After the switch is closed, which of the following statements is/are the possible outcome(s)?

(1) The ammeter burns out. (2) The voltmeter burns out. (3) The light bulb burns out.




18.

A ‘4 V, 10 W’ light bulb and a variable resistor R are connected to a 12 V battery as shown in the figure above. What is the resistance of the variable resistor if the bulb is operating at its rated value?

A. 0.8 Ω B. 1.6 Ω C. 2.4 Ω D. 3.2 Ω

19.

An electric kettle rated ‘220V, 1000 W’ is used in USA where the mains voltage is 110 V. The power consumed by the electric kettle is

A. 250 W. B. 500 W. C. 1000 W. D. 1250 W.


6 V

20 Ω

10 Ω 10 Ω

20.


Three resistors are connected to a 6 V battery as shown above. Which of the following statements are correct?

(1) The power dissipated in the two 10 Ω resistors are the same. (2) The total power dissipated in the resistors is 3.6 W. (3) The total power dissipated is larger if all resistors are connected in series.

A. (1) and (2) only B. (1) and (3) only

Q

R

P

circuit breaker

live neutral

C. (2) and (3) only D. (1), (2) and (3)

21.

The figure above shows 3 mains sockets connected to a ring circuit. Which of the following statements is/are correct?

(1) Only socket P is safe to use. (2) Only sockets P and Q will deliver a current. (3) Each of the sockets should be installed with a circuit breaker of its own.



22.


toaster

heating element

L N

The figure below shows a toaster. A fuse is installed to protect the toaster but the earth wire is missing. Which of the following statements is/are correct if the live wire accidentally touches the metal case of the toaster?

(1) The fuse will melt and break the circuit. (2) A large current will flow through the neutral wire. (3) The metal case will carry a high potential.


23.

The diagram above shows the label on an electric iron. Which of the following statements is/are correct when the electric iron is working at its rated value?

(1) The fuse installed in the plug of the electric iron should have a rating of 5 A. (2) The resistance of the electric iron is 44 Ω. (3) Suppose 1 kW h of electricity costs $0.86, the cost of running the electrical

appliance in 5 hours is $4.73..



24.


cardboard P and Q are two parallel straight wires carrying equal currents. The current in P

flows into the cardboard while the current in Q flows out of the cardboard. A compass is placed at point R midway between P and Q. In which of the following diagrams is the north pole of the compass needle pointing in the correct direction? The effect of the Earth’s magnetic field may be ignored.

A.

B.

C.

D.



25.

V

copper core The figure above shows a solenoid. Which of the following change(s) can

increase the strength of the magnetic field inside the solenoid? (1) Increase the length of the solenoid. (2) Remove the copper core. (3) Use thicker wire to make the solenoid.


- END OF SECTION A -


SECTION B Conventional Questions (80 marks)


Answer ALL questions in this section and write your answers in the spaces provided in this Question-Answer Book.

Question No. 1 2 3 4 5 6 7 8 9 10 11

Marks 8 6 8 8 5 7 11 6 6 11 4

1. Figure 1.1

Figure 1.1 shows an experimental arrangement used to study the double-slit interference of light from a filament lamp. The screen is placed at a distance D from the double-slit. The slit spacing of the double-slit is a.

Figure 1.2

The drawing in Figure 1.2 represents the resulting pattern when a yellow filter is used. Given the wavelength of yellow light is 640 nm.

(a) Find the separation of the yellow fringes. Show your working. (2 marks) _____________________________________________________________ _____________________________________________________________ _____________________________________________________________



(b) Find the value of a given D = 1.5 m. (2 marks) _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ (c) Describe and explain what happens to the pattern if, separately, (i) the yellow filter is replaced by a red filter, (2 marks) _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ (ii) the arrangement is immersed in water. (2 marks) _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________


2. Both X-ray and ultrasound are waves used in medical imaging.


(a) Suggest three differences between these two kinds of waves. (3 marks) _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________

(b) When performing ultrasound scanning, the ultrasound is NOT heard by the patient. Explain briefly. (1 mark)

_____________________________________________________________ _____________________________________________________________

(c) During an ultrasound scanning, an ultrasound pulse is emitted into the patient’s body by an apparatus called transducer. When the pulse reaches the organ, part of the pulse will be reflected and received by the transducer. Figure 2 shows this process.

Figure 2

A ultrasound pulse is emitted into the patient’s body and its echo is received after 7.5 × 10−5 s. How deep is the surface of the organ under the patient’s skin? The speed of sound in soft tissue and fat is 1540 m s−1. (2 marks)

_____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________



3. A beam of light is a mixture of two colour, red and blue. The light is incident

normally on a diffraction grating which has 4 × 105 lines per metre. Table 1 shows the diffraction angles measured from the normal of the grating for several orders of maximum.

1st order 2nd order 3rd order 4th order

Red A 35.2° 59.8° Not possible

Blue B 22.6° C 50.2° Table 1

(a) Using the values for the second order diffracting angles, calculate the wavelength of (4 marks)

(i) the red light: _____________________________________________ _____________________________________________ _____________________________________________ (i) the blue light: _____________________________________________ _____________________________________________ _____________________________________________ (b) Show that the 2nd order of red light coincides with the 3rd order of blue light. (2 marks) _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ (c) Using this grating, what is the maximum order of blue light? (2 marks) _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________


4.


Figure 4.1

Figure 4.1 shows a student stands beside a pool and finds a plastic box floating on the surface of still water. He wants to get the box and throws a stone into the water in order to set the box in motion.

(a) According to the direction of motion of the water molecules, state the kind

of wave produced on the water surface. (1 mark)

_____________________________________________________________ (b) How does the box move? (1 mark) _____________________________________________________________ (c) Explain whether the water waves can “push” the box to the student. (2 marks) _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________



Figure 4.2

(d) The pool has a deep region and a shallow region. Figure 4.2 shows a continuous water wave travelling towards the poolside.

(i) Name the wave phenomenon shown in Figure 4.2. (1 mark) _________________________________________________________

(ii) Deduce the relationship between the velocity of the water wave and the depth of water in the pool. Show your reasoning. (3 marks)

_________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________



5. Figure 5

Figure 5 shows the plants are sprayed with insecticide and the spray droplets are positively charged by a spray gun.

(a) Explain why the droplets do not stay together after leaving the gun. (1 mark) _____________________________________________________________ _____________________________________________________________

(b) Describe and explain two advantages of using charged droplets. (3 marks) _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ (c) Give another application of electrostatics in daily life. (1 mark) _____________________________________________________________


6.


Figure 6 Figure 6 shows two point charges Q1 (5 × 10−8 C) and Q2 (−2 × 10−8 C) separated

by 20 cm. X is a point between the two charges and is 8 cm away from Q1. (a) Find the magnitude of electric force acting on Q2. (2 marks) ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ (b) (i) Find the magnitude of electric field strength at X. (2 marks) ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________ (ii) State the direction of electric field strength at X. (1 mark) ________________________________________________________ (c) Find the electric potential at X. (2 marks) ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________



7. In an experiment, the electric potential V at different distances r from the centre of a charged metal sphere are measured and recorded in Table 2.

Distance from the centre

of the ball r / cm 10 20 30 40 50

Electric potential V / V 1100 450 210 100 20

r1 / m-1 10

Table 2

(a) Complete table 2 and then plot a graph of V against r1 . (5 marks)

Figure 7



(b) (i) Find the slope of the graph plotted in (a). (2 marks) _________________________________________________________ _________________________________________________________ _________________________________________________________

(ii) Hence, find the permittivity of free space. Given the charge on the metal ball is 1.49 × 10–8 C. (2 marks)

_________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ (c) An electric potential of 840 V is measured at position Y. From the graph

plotted in (a), estimate the distance from the centre of the ball to Y. (2 marks) _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________


8.


fan

9 V battery

conducting wires

Figure 8

A small fan rated ‘9 V, 18 W’ is connected to a 9 V battery as shown in Figure 8. The total resistance of the conducting wires is 1 Ω.

(a) What is the resistance of the fan? (2 marks) _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ (b) (i) Find the current flowing through the fan. (2 marks)

_________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ (ii) Find the voltage across the fan. (2 marks) _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________



9. Figure 9.1 Figure 9.2

Figure 9.1 shows a water tank. Usually, an indicator is installed in the tank to give information about the water level. The indicator consists of a simple circuit connected to a float inside the tank and Figure 9.2 shows the schematic diagram of the indicator. The resistance of the variable resistor in the circuit varies with the depth of the water.

(a) Briefly describe the working principle of the water level indicator.

(4 marks) _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________

(b) In the practical use of the water tank, the consumption of electricity is higher than the expected value. State one possible reason. (2 marks)

_____________________________________________________________ _____________________________________________________________ _____________________________________________________________


A B C

fuse box

10.


Figure 10.1

An unqualified technician connects three light bulbs to a 220 V mains supply as shown in Figure 10.1. The bulbs are designed to operate at 220 V. The power ratings of the bulbs A, B and C are 40 W, 60 W and 120 W respectively.

(a) (i) Do you think each of the bulbs will operate at its rated power when the

switch is closed? Explain briefly. (2 marks) _________________________________________________________ _________________________________________________________ _________________________________________________________

(ii) Which bulb is the brightest when the switch is closed? Explain briefly. (2 marks) _________________________________________________________ _________________________________________________________ _________________________________________________________

(b) (i) Draw a diagram to show a proper way of connecting the bulbs. (1 mark)

(ii) Then, find the total current drawn from the mains supply. (2 marks) _________________________________________________________ _________________________________________________________ _________________________________________________________



(c)

Meter No. Present reading Previous reading

1771771 51123 50812

(kWh) Figure 10.2 Figure 10.2 shows part of an electricity bill.

(i) How much energy, in Joules, is consumed? (1 mark) _________________________________________________________ _________________________________________________________

(ii) Suppose the charge rate of electricity is $0.87 / kW h. Calculate the cost of electricity. (2 marks)

_________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________

(iii) In Hong Kong, the charge rate of electricity actually increases with consumption. Suggest one advantage of this policy. (1 mark)

_________________________________________________________ _________________________________________________________ _________________________________________________________


11.


Figure 11 Four long parallel wires P, Q, R and S, each carrying current of 5 A, are placed at

the vertices of a square as shown in Figure 11. The directions of the currents of P, Q and R are out of the paper and that of S is into the paper. The distance between each wire and X is 2 cm.

(a) What is the direction of the magnetic field at X? (1 mark) ____________________________________________________________ (b) Find the magnitude of the magnetic field at X. (3 marks) ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________

- END OF SECTION B -

End of Paper

liu po shan memorial college (2010-11)

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