2010 h2 physics yjc

YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE















Candidate’s Name ………………………………….……… CTG ……………….…

YISHUN JUNIOR COLLEGE JC 2 Preliminary Examinations 2010

PHYSICS 9745,9646/1 HIGHER 2

27 August 2010

Paper 1 Multiple Choice Friday 1 hour 15 minutes

Additional Materials: Optical Mark Sheet

INSTRUCTIONS TO CANDIDATES

Do not open this booklet until you are told to do so.

Write your name and CTG on the Optical Mark Sheet in the spaces provided. Shade your CTG and Register Number in the space provided. There are forty questions in this paper. Answer all questions. For each question there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the separate Optical Mark Sheet. Read the instructions on the Optical Mark Sheet carefully. INFORMATION FOR CANDIDATES

Each correct answer will score one mark. A mark will not be deducted for a wrong answer.

Any rough working should be done in this booklet.

This question paper consists of 20 printed pages.

www.erwintuition.com


9745,9646/1/JC2Prelims/YJC2010

2

Data

speed of light in free space, c = 3.00 × 108 m s–1

permeability of free space, µ o = 4π × 10–7 H m–1

permittivity of free space, εo = 8.85 × 10–12 F m–1

(1/(36π)) × 10–9 F m–1

elementary charge, e = 1.60 × 10–19 C

the Planck constant, h = 6.63 × 10–34 J s

unified atomic mass constant, u = 1.66 × 10–27 kg

rest mass of electron, me = 9.11 × 10–31 kg

rest mass of proton, mp = 1.67 × 10–27 kg

molar gas constant, R = 8.31 J K–1 mol–1

the Avogadro constant, NA = 6.02 × 1023 mol–1

the Boltzmann constant, k = 1.38 × 10–23 J K–1

gravitational constant, G = 6.67 × 10–11 N m2 kg–2

acceleration of free fall, g = 9.81 m s–2

Formulae

uniformly accelerated motion, s = ut + 2

1at

2

v2 = u

2 + 2as

work done on/by a gas, W = p ∆ V

hydrostatic pressure, p = ρ g h

gravitational potential,

r

Gm−

Displacement of particle in s.h.m. x = xo sin ω t

velocity of particle in s.h.m., v = vo cos ω t

= ± ω )( 22

xxo

−

resistors in series, R = R1 + R2+……….

resistors in parallel,

R

1

........

11

21

++RR

electric potential,

r

Q

oπε4

alternating current/voltage, x = xo sin ω t

transmission coefficient T = exp(−2kd)

where k = 2

2 )(8

h

EUm −π

radioactive decay, x = xo exp(–λt)

decay constant, λ =

2

1

6930

t

.

φ =

=

V =




3

1 What are the base units of specific latent heat of fusion?

A m2 s-2

B kg-1 m2 s2

C m2 s2 K-1 D kg-1 m2 s2 K-1

2 The residents of a certain town would like the passenger train service that

passes through the town to make an additional stop at their station.

Graph A (in solid line) shows the time variation of the speed of a train that stops at the station whereas graph B (in dotted line) is for one that does not stop.

The total delay in making this additional stop is

A 320.0 s B 220.0 s C 190.0 s D 120.0 s

Speed / m s−1

Time / s

Graph B

Graph A

70.0 190.0 320.0

50.0

0

train just arrives

train leaves




4

3 The time variation of the acceleration of an object is as shown in the graph below.

At which point is the velocity the greatest?

4 The figure below shows the path of a ball leaving the ground at point X and about

to hit the ground at point Z.

If air resistance is negligible, the vertical component of

A velocity is maximum at Y B displacement is minimum at Y C velocity is the same at X and Z D acceleration is the same at Y as at Z

θ

initial velocity

X

Y

Z ground

A

B

C

D time

acceleration




5

5 A paratrooper jumps down from an aircraft and falls without significant drag force for 3 s before opening his parachute. Which of the following best shows the time t variation of his vertical acceleration a?

a

t/s

A

3

a

t/s

B

3

a

t/s

C

3

a

t/s

D

3




6

6 A trolley X of total mass 0.50 kg and speed 6.0 m s−1 approaches, head-on,

another trolley Y of total mass 0.60 kg and speed 5.0 m s−1 moving in the same direction along a level track. The collision is elastic with each trolley having a magnet with the like poles facing each other as shown below.

At some instant during the collision, X is at rest. The speed of Y then is

A 3.0 m s−1

B 5.0 m s−1

C 6.0 m s−1

D 10 m s−1

7 A uniform horizontal beam is acted upon by an upward push force, as shown

below, whose magnitude is equal to its weight.

The ends of the beam fit into sockets X and Y of two rigid vertical walls which keep the beam stationary. Which of the following correctly states the directions of the forces acting on the beam at X and Y?

Socket X Socket Y

A downwards upwards

B upwards upwards

C downwards downwards

D upwards downwards

weight

push

X Y

wall wall

X

6.0 m s−1

Y

5.0 m s−1

N S S N




7

8 Two rigid beams, 1 and 2, are fixed to a vertical wall. A stationary load of weight W is hung from point X where the two beams are joined as shown.

Which diagram shows the forces acting at X?

W

Beam 1

Beam 2

X

Force in Beam 1

Force in Beam 2

W

A

Force in Beam 1

Force in Beam 2

W

B

Force in Beam 1

Force in Beam 2

W

C

Force in Beam 1

Force in Beam 2

W

D




8

9 The base area of a barge is 80 m2 and the sides of the barge are vertical. The

depth h to which it rests in fresh water of density 1.0 × 103 kg m−3 is as shown on the left figure.

When further loaded, as shown on the right figure, with 5.0 × 103 kg of cargo, the

extra depth ∆h to which the barge will rest is A 0.063 m B 0.0064 m C 5.0 m D 610 m

10 A car of mass 1000 kg, traveling at 20 m s−1 on a level road comes to rest in a distance of 25 m. What is the work done against friction?

A 0.50 kJ B 8.0 kJ C 200 kJ D 250 kJ

After

barge

h

80 m2 Before

∆∆∆∆h




9

11 A ball of mass m and speed v, rolls up a slope from P to Q, a horizontal distance d away as shown. The distance PQ measured vertically is r and along the slope is s . What is the work done against the weight during the journey?

A mgs

B mgr

C mgd

D mg22

rd +

12 A car moves around a horizontal circular track at a constant angular speed ω.

Which of the following statements is true about the car’s motion? A Its linear velocity is constant B Its linear velocity is changing C Its linear acceleration is zero D Its linear acceleration is constant

ω

Car

Top view

P s

r

Q

d




10

13 A race car moves at a high speed along a banked circular track, as shown below. Which of the followings best represents the free-body diagram of the race car? A B C D 14 Planet X of mass M and planet Y of mass 3M revolve around a common centre.

The two planets are constantly separated by a distance of D. Where is this common centre of their rotation?

A 3

D from planet X

B 3

D from planet Y

C 4

D from planet X

D 4

D from planet Y

Side view

Centre of circular motion

Race car




11

15 A spring oscillates with a period of 1.0 s at a place where the acceleration of free fall is g. If it were to oscillate in another place where the acceleration of free fall is 2g, what would be the value of its new period?

A 0.5 s B 0.7 s C 1.0 s D 2.0 s 16 A particle P performs simple harmonic motion between points X and Y which are

4.0 cm apart . The time taken to move from X to Y is 0.8 s. What is the maximum speed of particle P?

A 5.0 x 10−2 m s−1

B 8.0 x 10−2 m s−1

C 16 x 10−2 m s−1

D 34 x 10−2 m s−1 17 Which one of the following is essential for the equation pV = nRT to be obeyed

by a real gas? A Changes should be at constant temperature B Changes should take place at constant volume C Pressures should be low D Temperatures must be higher than 273.15 K 18 Two coherent waves of intensities I and amplitude Y, meet in phase at a point.

Calculate, in terms of I and Y, the intensity and amplitude of the resultant wave at that point.

Intensity Amplitude

A 0 0

B I Y

C 2 I 2Y

D 4 I 2Y




12

19 Coherent monochromatic light illuminates two narrow parallel slits and the interference pattern which results is observed on a screen some distance beyond the slits. Which of the following will not affect the fringe separation of the interference pattern?

A Using monochromatic light of higher frequency

B Increasing the distance between the screen and the slits C Increasing the width of each slit D Increasing the distance between the slits 20 A thin copper rod is clamped at one end and made to vibrate by a driving force of

variable frequency applied to the free end. At specific frequencies, it is found that the rod resonates. Which of the following diagram is incorrect, where N and A represent a nodal and antinodal position respectively?

A

B

C

D

clamp

N A

clamp

N A N A N A

clamp

N A N A

clamp

N A N




13

21 Which of the following statements about an electric field is incorrect?

A The electric field strength due to a point charge proportionately with 1/r2 where r is the distance from the charge.

B The electric field strength at a point is a measure of the force exerted on a

unit positive charge at that point.

C The negative sign in the formula dr

dVE −= , implies that the field points

in the direction of decreasing potential. D The electric field strength at a point is equal to the potential gradient at

that point.

22 A point charge is placed at a point Y in front of an earthed metal sheet X. P and

Q are two points between X and Y as shown in the diagram. Which of the following mathematical relations between the electric field strengths E at different points is correct?

A EP = EQ

B EP = 0

C EP > EQ D EP < EQ 23 A 10 Ω resistor is connected across a cell of e.m.f 6.0 V and internal resistance

2.0 Ω. How much heat energy is dissipated by the resistor when 2 C of charge flows through it?

A 2.0 J B 10 J C 12 J D 40 J

P Q Y

X

point charge




14

24 Five identical resistors of resistance 2.0 Ω are connected as shown below. If the resistor R in the middle is removed from the circuit, what is the change in

the effective resistance across PQ? A Increase by 0.1 Ω B Increase by 0.4 Ω C Decrease by 0.4 Ω D Decrease by 2.0 Ω 25 In the circuit below, four resistors are connected in series with a 12 V battery.

One point along the circuit is earthed as indicated. What is the potential at point Z? A − 5.3 V B − 8.6 V C + 3.3 V D + 5.3 V

R

R

R

R

R

P Q

12 V

2.5 Ω 3.0 Ω 1.0 Ω 2.5 Ω

Point Z




15

26 Four identical bulbs labeled 1 to 4 are connected with a cell E in the circuit shown below.

Which of the followings will increase the brightness of bulb 1? A Replace the cell E with another cell of lower e.m.f B Remove bulb 2 C Connect another bulb in parallel with bulb 2 D Connect another bulb in series with bulb 4 27 A thermistor is connected in series with a fixed resistor of resistance R and a cell

of e.m.f 10 V, as shown in the diagram below. When the temperature of thermistor is 20°C, its resistance is 5.3 Ω and the

potential difference VT across it is 4.5 V. What is the value of VT if the temperature of thermistor increases to 60°C and the

resistance drops to 3.1 Ω? A 1.5 V

B 2.6 V C 3.2 V D 3.5 V

1

2

3

4

E

R

VT

10 V




16

28 Two identical magnets A and B are dropped from rest through the middle of a conducting ring. The ring for B has a small break in it as shown. Which of the following statements is correct?

A Magnet A has a smaller acceleration. B Magnet B has a smaller acceleration. C Both magnets fall through with the same acceleration D Both magnets fall through at constant velocity.

29 A rectangular coil with 200 turns has dimensions 5.0 cm by 4.0 cm. When the coil

is placed in a magnetic field B of 0.35 T and the current, I in the coil is 1.6 A, what is the value and direction of the maximum torque?

A 0.22 N m with the left edge moving into plane of paper B 5.6 N m with right edge moving into plane of paper C 0.22 N m with right edge moving into plane of paper D 11.2 N m with left edge moving into plane of paper

4.0 cm

I = 1.6 A 5.0 cm

B = 0.35 T

N

S

Magnet A

N

S

Magnet B




17

30 The figure below shows the circuit diagram for a half-wave rectifier. The supply to the rectifier is rated as 50 Hz , 6.0 V r.m.s. What is the average power dissipated in the load resistor, R = 2.0 Ω.

A 9.0 W B 18 W

C 25 W D 36 W

31 Transitions between the lowest three energy levels in a particular atom give rise

to three spectral lines of wavelength, in order of increasing magnitude, λ1, λ2 and

λ3. Which of the following correctly relates λ1, λ2 and λ3?

A λ1 + λ2 = λ3

B λ1 = λ2 + λ3

C 321

111

λλλ+=

D 321

111

λλλ=+

32 White light from a hot source is passed through sodium vapour and viewed

through a diffraction grating.

Which of the following best describes the spectrum seen? A Dark lines on a white background B Coloured lines on a white background C Coloured lines on a dark background D Dark lines on a coloured background

50 Hz 6.0 Vr.m.s

R




18

33 A beam of electrons are accelerated to hit a metal target and the corresponding X-ray spectrum is as shown below.

Which of the following statements is true of the features of the spectrum?

A Increasing the accelerating voltage increases λ1

B Changing the type of metal changes λ1

C Both I2 and λ2 decrease when the electron beam is made less intense

D I3 includes the number of X-ray photons of wavelength λ3 emitted by the ‘braking radiation’ process.

34 The uncertainty in the de Broglie wavelength of an electron was found to be 1 ×

10−10 m. Its uncertainty in position is thus

A 1 × 10−9 m

B 1 × 10−10 m

C 8 × 10−12 m

D 5 × 10−45 m 35 In terms of band theory, which of the following is one of the main features which

explains the electrical properties of intrinsic semiconductors?

A More valence electrons B Smaller energy band gap C More holes D More energy levels

36 Which of the following terms is not applicable to photons produced by stimulated

emission?

A Coherent B Parallel C In Phase D Polarised

Intensity

Wavelength 0

λ1 λ2 λ3

I3

I2




19

37 Which of the following is true about extrinsic semiconductors?

A Extrinsic semiconductors can only be made by doping silicon with either arsenic or boron.

B p-type extrinsic semiconductors are positively charged. C Extrinsic semiconductors have higher conductivity compared to intrinsic

semiconductors. D Extrinsic semiconductors have larger energy band gaps compared to

intrinsic semiconductors.

38 For the same given p-n junction, which circuit below gives the widest depletion region?

A

B

C

D

p n

p n

p n

p n




20

39 A Thorium-234 nucleus decays and undergoes two beta-particle emissions, one alpha-particle emission and one unknown emission to form the Radium-226 nucleus.

What could be the unknown emission? A Alpha-particle emission B Beta-particle emission C Gamma emission

D Neutron emission

40 A stationary uranium nucleus, U23892 undergoes radioactive decay with emission

of a helium nucleus, He42 of kinetic energy E. What is the kinetic energy of the

daughter nucleus?

A E234

4

B E238

4

C E

D E4

238

End Of Paper















Candidate’s Name ……………………………… CTG ……….…

YISHUN JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION 2010

PHYSICS 9646/2 HIGHER 2

19 August 2010 Paper 2 Thursday 1 hour 45 minutes

INSTRUCTIONS TO CANDIDATES Write your name and CTG in the spaces at the top of this page. Write your answers in the spaces provided on the question paper. You must use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions. It is recommended that you spend about 1 hour 15 minutes on this section. Section B Answer Question 8. It is recommended that you spend about 30 minutes on this section. The number of marks is given in brackets [ ] at the end of each question or part question.

This question paper consists of 17 printed pages

For Examiner’s Use

Paper 2

1 /7

2 /7

3 /7

4 /7

5 /9

6 /5

7 /18

8 /12

Total /72



9646(New Syllabus)/2/JC2Prelims/YJC2010

2

Data

speed of light in free space, c = 3.00 × 108 m s-1

permeability of free space, µ o = 4π × 10-7 H m-1

permittivity of free space, εo = 8.85 × 10-12 F m-1

= (1/(36π)) × 10−9 F m-1

elementary charge, e = 1.60 × 10-19 C

the Planck constant, h = 6.63 × 10-34 J s

unified atomic mass constant, u = 1.66 × 10-27 kg

rest mass of electron, me = 9.11 × 10-31 kg

rest mass of proton, mp = 1.67 × 10-27 kg

molar gas constant, R = 8.31 J K-1 mol-1

the Avogadro constant, NA = 6.02 × 1023 mol-1

the Boltzmann constant, k = 1.38 × 10-23 J K-1

gravitational constant, G = 6.67 × 10-11 N m2 kg-2

Acceleration of free fall g = 9.81 m s-2

Formulae

uniformly accelerated motion, s = ut + ½at2

v2 = u

2 + 2as




r

Gm−



= ± ω )( 22xx

o−


Resistors in parallel, R

1 ........

11

21

++RR

electric potential,

r

Q

oπε4


transmission coefficient T = exp(−2kd), where k =2

2

h

E)m(U8π −

radioactive decay, x = xo exp(-λ t)

decay constant, λ = 2/1

693.0

t

φ =

=

V =




3

Section A Answer all questions.

It is recommended that you spend about 1 hour 15 minutes on this section. 1 (a) State Newton’s law of gravitation. [2]

..………………………………………………………………………………… ..…………………………………………………………………………………

..…………………………………………………………………………………

(b) A source reported that Singapore plans to launch a satellite that will

orbit around the Earth at 2.5 × 103 m above its surface in the year

2020. Take the radius of Earth to be 6.38 × 106 m and mass of

Earth to be 5.97 × 1024 kg.

(i) Calculate the linear velocity of the satellite when in orbit. [2]

Linear velocity = …………….. m s−1

(ii) Deduce whether the satellite is geostationary. [2]

(iii) If the satellite were to orbit above the equator, state the

direction of launch, in order to minimize energy required. [1] ………………………………………………………………………………




4

2 Fig. 2.1 shows a potentiometer circuit that can be used to determine the unknown e.m.f. of a test cell. The driver cell has an e.m.f. of 12 V and internal resistance of 1.5 Ω. The resistance of the rheostat can vary between 0.0 Ω and 5.0 Ω and the resistance wire has a length of 1.2 m.

(a) When the resistance of rheostat is 2.3 Ω, the balance length is 0.57 m. When the resistance of rheostat is changed to 3.5 Ω, the balance length becomes 0.68 m. Calculate the e.m.f. of the test cell and the resistance of the 1.2 m long resistance wire. [4]

Emf of test cell = ……………….. V

Resistance of 1.2 m long resistance wire = ……………….. Ω

(b) State what will happen to the balance length if the internal resistance of the test cell is doubled. [1] ………………………………………………………………………………………

Fig. 2.1

12 V, 1.5 Ω

Test cell

0.0 – 5.0 Ω

1.2 m long resistance wire




5

(c) Explain why the resistance of the rheostat cannot be higher than a

particular value, if the potentiometer is to be able to determine the unknown e.m.f. [2] ……………………………………………………………………………………… ………………………………………………………………………………………

3 A narrow beam of electrons at a speed of 3.2 × 107 m s1 travels along a circular path in a uniform magnetic field of flux density, B, as shown in Fig. 3.1 below.

Fig. 3.1

(a) (i) Explain why the electrons undergo uniform circular motion. [3]

..………………………………………………………………………………...… ..…………………………………………………………………………………... ..………………………………………………………………………………...… ..…………………………………………………………………………………

B

incident beam of electrons




6

(ii) Show that the speed, v, of the electrons in the field is given by

m

Berv =

where r is the radius of the circular path of the beam in the field.

[2]

(iii) The radius of the circular path of the beam in the field was found to be 25

mm. Determine the magnetic flux density of the field.

Flux density = ….................... T [2]




7

4 A circular coil of diameter 140 mm has 850 turns. It is oriented so that its plane is perpendicular to a horizontal magnetic field of uniform flux density 45 mT, as shown in Fig. 4.1.

Fig. 4.1

(a) Calculate the magnetic flux passing through the coil in this position.

Magnetic flux = ….................... Wb [2]

(b) The coil is rotated through 90° about the vertical axis shown in a time of 120 ms.

(i) Calculate 1. the change of magnetic flux linkage produced by this rotation, and

change of magnetic flux linkage produced = ….................... Wb [2]

vertical axis

uniform magnetic field coil of 850 turns




8

2. the average e.m.f induced in the coil during this rotation.

Average e.m.f. induced = ….................... V [1]

(ii) State and explain what will happen to the value of the average e.m.f induced if the coil is rotated through 360°.

..………………………………………………………………………………… ..………………………………………………………………………………… ..………………………………………………………………………………… …....………………………………………………..……………………..………[2]

5 (a) A heating device is designed to operate on either an a.c. or d.c. power supply.

The device has a resistance of 6.0 Ω. Calculate the average power dissipated in the device when operating at

(i) an a.c. supply of voltage 12.0 V, 50 Hz

average power dissipated = …………. W [2]




9

(ii) a d.c. supply of voltage 12.0 V

average power dissipated = …………. W [1]

(b) Draw the time t variation of the power P dissipated in the device for both the a.c. and d.c. supply on the same axes below. Mark values on both axes.

[4]

(c) The alternating supply of voltage 12.0 V, 50 Hz is derived from the mains supply of voltage 230 V, 50 Hz using a transformer, assumed to have 100% efficiency.

Calculate the primary r.m.s. current when the heating device is in use.

primary r.m.s. current = …………….. A [2]

P / W

t / s




10

6 In a three-level ruby laser, light of wavelength 550 nm from a flash lamp is

used to excite the atoms in the ruby from ground state E1 to state E3. In subsequent de-excitations, laser light is emitted. The energy levels are as shown in Fig. 6.1.

(a) Draw, on Fig. 6.1, the transition that produces the laser light. [1] (b) (i) Explain why a metastable state is required for population inversion.

..………………………………………………………………………………… ..…………………………………………………………………………………

[1] (ii) Explain why population inversion is necessary for lasing to work.

..………………………………………………………………………………… ..…………………………………………………………………………………

[1]

(c) Explain the function of the reflective surfaces in the laser.

..………………………………………………………………………………… ..…………………………………………………………………………………

..…………………………………………………………………………………

[2]

E1

E2*

E3

Fig. 6.1




11

7 Jupiter has many moons with different orbital period T (in days) and

average orbital radius r (in × 109 m). Data for six of them are shown in the table of Fig. 7.1 below.

Moon T / days r / ×××× 109 m

Sinope 758 23.7 Leda 239 11.1 Callisto 16.7 1.88

Europa 3.55 0.671

Io 1.77 0.422

Metis 0.295 0.128

Fig. 7.1

(a) Suggest why the values of r are averages. [1] ……………………………………………………………………………………… ……………………………………………………………………………………… (b) It is expected that the moons obey the relation

T r n = k

where n and k are constants.

Explain how the relation may be tested by plotting a graph of lg T against lg r. [3]

……………………………………………………………………………………… ……………………………………………………………………………………… ………………………………………………………………………………………




12

(c) Some data from Fig. 7.1 are used to plot the graph of Fig. 7.2.

Fig. 7.2

(i) On Fig. 7.2,

1. Plot the point corresponding to Callisto. Label it C. [2] 2. Draw the line of best fit for the six points. [1]

8.0 8.5 9.0 9.5 10.0 10.5 11.0 lg (r / m)

3.0

2.5

2.0

1.5

1.0

0.5

0.0

−0.5

−1.0

lg (T / days)

4.0

3.5




13

(ii) From (i), determine the magnitudes of the constants n and k. [4]

n = ……………..

k = ……………..

(iii) Explain whether the answer to (ii) is in agreement with Kepler’s

Third Law. [2]

……………………………………………………………………………………… ………………………………………………………………………………………

(iv)Another moon, Thermisto has a period of 130 days. Use Fig. 7.2 to

estimate the orbital radius of Thermisto. [2]

radius = ………………….. m

(v) Earth’s moon has an orbital radius of 0.384 × 109 m. 1. Plot its corresponding point. Label it E. [2] 2. Suggest why point E deviates from the line of best fit. [1]

……………………………………………………………………………………… ………………………………………………………………………………………




14

Section B It is recommended that you spend about 30 minutes on this section.

8 Students are shown a demonstration illustrating some principles of

electromagnetic induction.

A coil is wrapped around the full length of a vertical Perspex tube through which a soft iron rod is inserted. An aluminium ring is placed over the upper end of the rod. When released from rest, the ring falls freely down the gap between the rod and the Perspex tube. The time taken for the aluminium ring to fall from the top to the bottom of the Perspex tube is noted. When an alternating current is passed through the coil, the time taken for the aluminium ring to fall from the top to the bottom of the Perspex tube is seen to increase slightly.

Design an experiment to investigate how the time for the aluminium ring to fall from the top to the bottom of the Perspex tube is affected by a chosen factor of the experimental arrangement. You should assume that the normal laboratory apparatus used in schools and colleges is available. You may wish to draw a diagram to illustrate your answer.

aluminium ring

Perspex tube

coil

soft iron rod

gap




15

Your answer should contain details of (a) the procedure to be followed including which measurements would be

taken, (b) how you propose to use your measurements to obtain reliable results for

the investigation. (c) any factors you will need to control and how you will do this. (d) any particular features of your design which may improve the accuracy of

your experiment. [12]

Diagram




16

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Candidate’s name ………………………………. CTG ……….…

YISHUN JUNIOR COLLEGE JC 2 Preliminary Examinations 2010

PHYSICS 9745, 9646/3 HIGHER 2

26 August 2010 Paper 3 Thursday

2 hours

INSTRUCTIONS TO CANDIDATES Write your name and CTG in the spaces at the top of this page. Write your answers in the spaces provided on the question paper. For numerical answers, all working should be shown clearly. Section A Answer all questions. Section B Answer any two questions. INFORMATION FOR CANDIDATES The number of marks is given in brackets [ ] at the end of each question or part question.

This question paper consists of 19 printed pages

For Examiner’s Use

Section A

1 /8

2 /8

3 /8

4 /8

5 /8

Section B

6 /20

7 /20

8 /20

Penalty

Total /80

Candidates answer on the Question Paper. No Additional Materials are required.



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Data

speed of light in free space, c = 3.00 × 108 m s–1

permeability of free space, µ o = 4π × 10–7 H m–1

permittivity of free space, εo = 8.85 × 10–12 F m–1

(1/(36π)) × 10–9 F m–1

elementary charge, e = 1.60 × 10–19 C

the Planck constant, h = 6.63 × 10–34 J s

unified atomic mass constant, u = 1.66 × 10–27 kg

rest mass of electron, me = 9.11 × 10–31 kg

rest mass of proton, mp = 1.67 × 10–27 kg

molar gas constant, R = 8.31 J K–1 mol–1

the Avogadro constant, NA = 6.02 × 1023 mol–1

the Boltzmann constant, k = 1.38 × 10–23 J K–1

gravitational constant, G = 6.67 × 10–11 N m2 kg–2

acceleration of free fall, g = 9.81 m s–2

Formulae

uniformly accelerated motion, s = ut + 2

1at

2

v2 = u

2 + 2as




r

Gm−



= ± ω )( 22xx

o−


resistors in parallel,

R

1

........

11

21

++RR

electric potential,

r

Q

oπε4


transmission coefficient T = exp(−2kd)

where k = 2

2 )(8

h

EUm −π

radioactive decay, x = xo exp(–λt)

decay constant, λ = 2

1

6930

t

.

φ =

=

V =



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[Turn over

Section A Answer all the questions in this section.

1 A car that is moving along a horizontal road may be considered to have three forces

acting on it as shown in Fig. 1.1 below.

(a) Explain why X and Z are resultant forces. [2] ………………………………………………………………………………………………………

……………………………………………………………………………………………………… ………………………………………………………………………………………………………

(b) The car and its contents have a total mass of 1200 kg. Force Y is horizontal and

has magnitude 2000 N. If the car is accelerating at 8 m s−2, calculate 1. the magnitude of force Z 2. the angle that Z makes with the road

[6]

magnitude of Z = ………..…….. N

angle = ………….. °

Resultant force X of Earth on car

Resultant force Y of air on car

Resultant force Z of road on car

Fig. 1.1



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2 (a) (i) Derive the equation

Ep = mgh

where Ep is the change in potential energy of a mass m moved through a vertical distance h near the Earth’s surface. [2]

(ii) Explain why the above equation is not valid for masses placed at very large distances away from the Earth’s surface. [2]

......………………………………………………………………………………………… ……………………………………………………………………………………………… ………………………………………………………………………………………………

(b) (i) Fig. 2.1 shows data for ethanol.

Density 0.79 g cm-3

Specific heat capacity of liquid ethanol 2.4 J g-1 K-1

Specific latent heat of fusion 110 J g-1

Specific latent heat of vaporisation 840 J g-1

Melting point -120 oC

Boiling point 78 oC

Fig 2.1

Use the data in Fig. 2.1 to calculate the thermal energy required to convert 1.0 cm3 of ethanol at 20 oC into vapour at its normal boiling point. [3]



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Thermal energy required = ………..…….. J

(ii) Suggest why there is a considerable difference in magnitude between its specific latent heat of fusion and vaporization. [1]

………..…………………………………………………………………………………… ………..……………………………………………………………………………………

………..……………………………………………………………………………………

3 In the recently opened Universal Studios, one of the roller coaster sections includes a

loop-a-loop that looks like the one shown in Fig. 3.1. The radius of the loop is 18.0 m and the centre of the loop is 20.0 m from the ground.

(a) If the mass of a coaster car is 250 kg and there is no support system holding the

car to the track, calculate

(i) the minimum speed at the top of the loop required for the car to stay in contact with the track, [2]

Minimum speed at the top of loop = ………………….. m s−1

Fig. 3.1

18.0 m

20.0 m Coaster car



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(ii) the minimum speed the car needs to have when it enters the loop, if the

car loses 15.0 J of energy per unit length of track travelled, and [3]

Minimum speed when entering loop = …………………… m s−1

(iii) the vertical force exerted by the track on the car when the car just enters

the loop. [2]

Vertical force exerted by track = ………………….. N

(b) Explain why is the magnitude of the force calculated in (a) (iii) not equal to the

weight of the car. [1] ……….………..…………………………………………………………………………………… ……….………..……………………………………………………………………………………



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4 (a) Explain, using one of the observations of the photoelectric effect experiment, how the effect illustrates the particulate nature of electromagnetic radiation. [3]

……….………..……………………………………………………………………………………

……….………..……………………………………………………………………………………

……….………..……………………………………………………………………………………

……….………..……………………………………………………………………………………

……….………..……………………………………………………………………………………

(b) The lifetime of an electron in the ground state of an atom is very long. Explain why this implies that the energy of the ground state is well-defined. [2]

……….………..……………………………………………………………………………………

……….………..…………………………………………………………………………………… ……….………..…………………………………………………………………………………… ……….………..……………………………………………………………………………………

(c) Fig. 4.1 below shows how the potential energy Ep of an α-particle varies with distance r along a line from the centre of a nucleus where Ro is the nuclear radius.

Using this graph, suggest why nuclei that emit high energy α-particles have short half-lives. [3]

……….………..……………………………………………………………………………………

……….………..……………………………………………………………………………………

……….………..……………………………………………………………………………………

……….………..……………………………………………………………………………………

……….………..……………………………………………………………………………………

……….………..……………………………………………………………………………………

Ep

r

Fig. 4.1

0 Ro



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5 (a) As temperature increases, a semiconductor has greater conductivity whereas a resistance wire has greater resistivity. Explain why this is so, in terms of charge carriers. [2]

……….………..…………………………………………………………………………………… ……….………..…………………………………………………………………………………… ……….………..…………………………………………………………………………………… ……….………..……………………………………………………………………………………

(b) Fig. 5.1 shows the possible energy band structure of an intrinsic semiconductor. The valence band is completely filled and there is no charge carrier in the conduction band. Explain in terms of charge carriers and energy band structure how conduction is possible. [2]

……….………..…………………………………………………………………………………… ……….………..…………………………………………………………………………………… ……….………..…………………………………………………………………………………… ……….………..……………………………………………………………………………………

(c) Explain the origin of the depletion region in a p-n junction. [2]

……….………..……………………………………………………………………………………

……….………..……………………………………………………………………………………

……….………..……………………………………………………………………………………

……….………..……………………………………………………………………………………

Valance band

Conduction band

Fig. 5.1



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(d) Draw a labelled circuit diagram to show how the depletion region of a p-n junction can be reduced or removed. [2]



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Section B Answer two questions in this section.

6 (a) Explain what is meant by simple harmonic motion. [2]

……….………..……………………………………………………………………………………

……….………..…………………………………………………………………………………… ……….………..……………………………………………………………………………………

……….………..……………………………………………………………………………………

(b)

Fig. 6.1 shows floating beads P and Q, 5.0 cm apart, on the surface of the water. They will oscillate vertically when a wave passes through from P to Q. The displacement x

versus time t graph of P is shown in Fig. 6.2. The speed of the wave is 2.5 cm s−1.

(i) Write an equation to describe the variation of x of P with t. [1]

(ii) Calculate the maximum speed of P. [2]

Maximum speed = ………………….. m s−1

5.0 cm P Q

1.0 2.0 3.0 t /s

x /cm

2.5−

Fig. 6.2 −2.5 −

Fig. 6.1

water



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(iii) The amplitude of Q is 2.0 cm. Calculate its maximum speed. [1]

Maximum speed = ……….………… m s−1

(iv) Calculate the phase difference between P and Q. [2]

Phase difference = …………………. radian

(v) Draw a displacement versus distance graph to show the damping of the wave from P to Q and beyond. [2]



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(c) White light has a wavelength range from 400 nm to 750 nm. A diffraction grating with 6 × 105 lines per metre is placed at right angles to a ray of white light and produces the first and second order spectra as shown in Fig. 6.3.

(i) Show, by calculation, that the angle β is greater than α. [4]

(ii) Show, by calculation, whether the second order spectrum overlaps with the

third order spectrum. [3]

First order spectrum α

β

Second order spectrum

White light

Fig. 6.3

A



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(iii) State two advantages of analysing the light in the first order spectrum. [2] ………..……………………………………………………………………………………

………..……………………………………………………………………………………

………..……………………………………………………………………………………

………..……………………………………………………………………………………

(iv) State what would be seen at A. [1]

………..……………………………………………………………………………………

7 (a) (i) Define electric field strength and state the SI unit in which it is measured. [2] ………..……………………………………………………………………………………

………..…………………………………………………………………………………… ………..…………………………………………………………………………………… ………..……………………………………………………………………………………

(ii) Two charged parallel plates are separated by a distance d and have a potential difference V between them. Write down an expression for the electric field strength of the uniform field between the plates. [1]



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(b) Fig. 7.1 illustrates two plates A and B, at a distance 30 mm apart in a vacuum, with plate A at a potential of − 4.2 V and plate B at a potential of − 2.0 V.

(i) Draw arrows to represent the electric field between the plates. [1] (ii) Calculate the magnitude of this electric field strength. [2]

Magnitude of electric field strength = ………………

(iii) An electron, β1 is emitted from plate B in a direction normal to its surface

and moves directly towards plate A. Calculate the minimum velocity, v1 with which the electron needs to be emitted in order to reach plate A. [2]

Minimum velocity = ………………… m s-1

(iv) State, with a reason, how your answer in (b) (iii) may be affected if

1. the distance between the plates had been halved to 15 mm, while keeping the potential difference the same. [2]

.……………………………………………………………………………………

……….……………………………………………………………………………

….…………………………………………………………………………………

..……………………………………………………………………………………

30 mm

θ

β2

Plate A − 4.2 V

Plate B − 2.0 V

β1

v1 v2

Fig. 7.1



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2. the potential of plate A is changed to + 4.2 V and potential of plate B is changed to + 2.0 V while keeping the distance between the plates at 30 mm. [2]

.……………………………………………………………………………………

……….……………………………………………………………………………

….…………………………………………………………………………………

..……………………………………………………………………………………

(v) Another electron, β2 is emitted from plate B with a velocity v2 = 1.1×106 m s−1 at an angle θ to the normal as shown in Fig 7.1. Determine the largest possible angle θ which would allow the electron to just reach plate A. [2]

Largest possible angle = ……….. °



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(c) The potentials of plates A and B are now changed to + 0.29 V and 0 V respectively. A charged micro-particle is suspended between the two plates as shown in Fig. 7.2 below.

(i) State the sign of charge present on the particle. [1]

………..……………………………………………………………………………………

(ii) Find the charge to mass ratio, q/m of the particle. [2]

q/m = ………………… C kg-1

(iii) A student claims that the mass of the particle is 72 × 10−19 kg. Based on your answer to part (c) (ii), explain why his answer is not valid. [3]

………..……………………………………………………………………………………

………..……………………………………………………………………………………

………..……………………………………………………………………………………

………..……………………………………………………………………………………

………..……………………………………………………………………………………

………..……………………………………………………………………………………

30 mm

Plate A + 0.29 V

Plate B 0 V

Fig. 7.2



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8 (a) Explain what is meant by nuclear fission. [2] ……….………..…………………………………………………………………………………… ……….………..……………………………………………………………………………………

(b) A typical nuclear fission reaction that involves uranium-235 is represented by the equation

n3BaKrnU 141

56

92

36

235

92 ++→+

Data:

Nucleus Mass in u

U235

92 235.044

Kr92

36 91.910

Ba141

56 140.916

n 1.009

(i) Deduce the number of protons and neutrons in the Kr92

36 nucleus.

[2]

Number of protons = ………………….

Number of neutrons = ………………….

(ii) Calculate the energy released, in joules, in the above reaction. [3]

Energy released = ……………………… J



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(iii) If a nuclear power station uses up U235

92 at a rate of 3.5 × 10−3 kg s−1 and

has an efficiency of 23%, estimate the useful power output. [3]

Useful power output = ……………………… W

(iv) State two forms of energy of the product particles. [2] ……….………..…………………………………………………………………………………… ……….………..……………………………………………………………………………………

……….………..……………………………………………………………………………………

(c) Uranium-234 is another isotope of uranium that is radioactive and has a half-life of 2.4 × 105 years. The daughter nuclei from the decay is Thorium-230 with the emission of another particle X.

(i) Define half-life. [1]

………..……………………………………………………………………………………

………..……………………………………………………………………………………

(ii) Suggest what X is. [1]

………..……………………………………………………………………………………

(iii) Calculate the decay constant of Uranium-234. [1]

Decay constant = ……………………… year−1



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(iv) Calculate the activity of a U-234 source after 8.7 × 104 years if it initially has 5.5 × 1026 atoms. [3]

Activity = …………………… year−1

(v) Describe two applications of radioisotopes. [2]

………..……………………………………………………………………………………

………..……………………………………………………………………………………

………..……………………………………………………………………………………

………..……………………………………………………………………………………

………..……………………………………………………………………………………

~ END OF PAPER ~



2010 h2 physics yjc

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