2010 YJC H2 Phy_Paper2_Qn

YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGEYISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGEYISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGEYISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGEYISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGEYISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGEYISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGEYISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGEYISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGEYISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGEYISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGEYISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE

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

YISHUN JUNIOR COLLEGEJC 2 PRELIMINARY EXAMINATION 2010

PHYSICS 9646/2HIGHER 2

19 August 2010Paper 2 Thursday

1 hour 45 minutes

INSTRUCTIONS TO CANDIDATESWrite 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 AAnswer all questions.It is recommended that you spend about 1 hour 15 minutes on this section.

Section BAnswer 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.

For Examiner’s UsePaper 2

1 /7

2 /7

3 /7

4 /7

5 /9

6 /5

7 /18

8 /12

Total /72

This question paper consists of 17 printed pages

9646(New Syllabus)/2/JC2Prelims/YJC2010

2

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

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

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

= (1/(36)) 109 F m-1

elementary charge, e = 1.60 10-19 C the Planck constant, h = 6.63 10-34 J sunified atomic mass constant, u = 1.66 10-27 kgrest mass of electron, me = 9.11 10-31 kgrest mass of proton, mp = 1.67 10-27 kgmolar 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 = u2 + 2aswork done on/by a gas, W = p V

hydrostatic pressure, p = g h

gravitational potential,

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

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

=

resistors in series, R = R1 + R2+……….

Resistors in parallel,

electric potential,

alternating current/voltage, x = xo sin t

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

radioactive decay, x = xo exp(- t)

decay constant, =

Section A9646(New Syllabus)/2/JC2Prelims/YJC2010

=

=

V =

3

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]

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(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]

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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


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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]

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(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]

………………………………………………………………………………………9646(New Syllabus)/2/JC2Prelims/YJC2010

Fig. 2.1

12 V, 1.5 Ω

Test cell

0.0 – 5.0 Ω

1.2 m long resistance wire

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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]

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


B

incident beam of electrons

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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]

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.


vertical axis

uniform magnetic field coil of 850 turns

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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]

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


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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°.

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

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


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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]

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.


E1

E2*

E3

Fig. 6.1

P / W

t / s

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(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.

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

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

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[2]


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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 mSinope 758 23.7Leda 239 11.1Callisto 16.7 1.88Europa 3.55 0.671Io 1.77 0.422Metis 0.295 0.128

Fig. 7.1

(a) Suggest why the values of r are averages. [1]

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(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]

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(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]

(ii) From (i), determine the magnitudes of the constants n and k. [4]9646(New Syllabus)/2/JC2Prelims/YJC2010

8.0 8.5 9.0 9.5 10.0 10.5 11.0lg (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

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n = ……………..

k = ……………..

(iii) Explain whether the answer to (ii) is in agreement with Kepler’s Third Law. [2]

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(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]

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………………………………………………………………………………………Section B

It is recommended that you spend about 30 minutes on this section.9646(New Syllabus)/2/JC2Prelims/YJC2010

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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.

Your answer should contain details of


aluminium ring

Perspex tube

coil

soft iron rod

gap

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(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

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END OF PAPER


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2010 YJC H2 Phy_Paper2_Qn

Documents

yishun junior college

v resistance

resistance of rheostat

internal resistance

long resistance wire

question paper

decay constant

gravitational constant