Mock Prelim 2012 H2 Paper 3

7/27/2019 Mock Prelim 2012 H2 Paper 3

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TEMASEK JUNIOR COLLEGE2012 Mock Preliminary ExaminationHigher 2

NAME CG

CENTRENUMBER

INDEXNUMBER

PHYSICS

Paper 3 Longer Structured Questions

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

9646/03

2 hours

READ THESE INSTRUCTIONS FIRST

Write your name and C.G. on all the work you hand in.Write in dark blue or black pen on both sides of the paper.You may use a soft pencil for any diagrams, graphs or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.

Section AAnswer allquestions.

Section BAnswer any two questions.

For Examiners Use

You are advised to spend about one hour on each section. 1

The number of marks is given in brackets [ ] at the end of each questionor part question.

2

At the end of the examination, circle the numbers of the Section Bquestions you have answered in the grid provided.

3

4

5

6

7

8

Total

This document consists of 17printed pages.[Turn over


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Data

Formulae

uniformly accelerated motion, s = ut + at2

v2 = u2+ 2as

work done on/by a gas, W = p V

hydrostatic pressure, p = gh

gravitational potential, f = /Gm r-

displacement of particle in s.h.m. x = xosint

velocity of particle in s.h.m. v = vocos t

= ( )22 xxo -w

resistors in series, R = R1+ R2+

resistors in parallel, 1/R = 1/R1+ 1/R2+

electric potential, V = Q / 4 or

alternating current/voltage, x = xosinttransmission coefficient, T = exp(-2kd)

where k = ( )22

8 m U E

h

p -

radioactive decay, x = xoexp(-t)

decay constant =

21

693.0

t

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

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

permittivity of free space, o = 8.85 x 10-12Fm-1

(1 / (36 )) x 10-9Fm-1

elementary charge, e = 1.60 x 10-19C

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

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

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

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

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

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

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

gravitational constant, G = 6.67 x 10-11N m2kg-2

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


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Section A

Answer allthe questions in the spaces provided.It is recommended that you spend about one hour on this section.

1 In a nuclear reactor, a fast moving neutron with initial speed u1makes a head-on elasticcollision with a stationary nucleus of carbon-12. The speed of the neutron and the carbonnucleus after the collision are v1and v2respectively as shown in Fig. 1.1.

(a) What is meant by head-onand elastic?

[2]

(b) In an elastic collision, the relative speed of separation is equal to the relative speed ofapproach. Write an equation in terms of the velocities given to illustrate this fact.

[1]

(c) By considering your answer to (b), find the ratio of the final speed of the neutron v1to itsinitial speed u1.

ratio = [3]

(d) Hence determine the fraction of the kinetic energy of the neutron that is transferred to

the carbon nucleus.

fraction = [3]

u1 v

v2Before collision After collision

Fig 1.1neutron carbon nucleus neutron carbon nucleus


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2

2 (a) An object is travelling with constant speed v on a circular path of radius r, as shown inFig. 2.1.

The object moves from position 1 to position 2 in a short period of time. On Fig. 2.2,draw labelled lines to complete a vector diagram to show the change in velocity thattakes place between position 1 and position 2. The velocity vector at position 1 isalready drawn for you.

[2]

(b) A roller-coaster ride in a theme park is illustrated in Fig. 2.3.

The total mass of carriage and passengers is 560 kg. It has a speed of 10.0 m s 1atthe top of the descent. The height of the descent is 25.0 m. At point B, the bottom ofthe descent, the carriage is on a path of radius 18.0 m.

Fig. 2.1

Fig. 2.2

Fig. 2.3


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3

(i) Calculate the speed of the carriage at B, the bottom of the descent, if 40 000 J islost as frictional heating during the descent.

speed = m s-1 [3]

(ii) Calculate the magnitude of the force exerted by the track on the carriage at B.

force = N [3]

3 A sample of an ideal gas passes through the cycle of ABCD shown on the P-V diagram inFig 3.1.

Fig. 3.1


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(a) The first law of thermodynamics states that DU = q + W.

Suggest how the state of an ideal gas may be changed such that each of thefollowing conditions is met separately.

DU = 0

W = 0 [2]

(b) During the change AB, 300 J of thermal energy is supplied to the gas.Determine the change in internal energy of the gas.

change in internal energy = J [2]

(b) During the change BC, 250 J of thermal energy is transferred. The area ABCon the P-V diagram represents 120 J of energy. Calculate the thermal energy

transfer during the change CA.

thermal energy transfer = [2]


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5

4 (a) In the circuit shown in Fig 4.1, a battery of e.m.f. 10 V with negligible internal

resistance I connected to a potentiometer wire of 1.20 m, an ammeter and someresistors.

Fig. 4.1

Given that the resistivity of the potentiometer wire is 2.5 x 10-3 m whose cross-sectional area has a diameter of 1.6 x 10-3m,

(i) Calculate the resistance of the potentiometer wire.

resistance = W [3]

(ii) Hence, determine the potential difference VXY across the potentiometerwire.

VXY = V [3]


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(b) Another battery of unknown e.m.f. E of negligible resistance is added to the circuit asshown in Fig 4.2. The wire connecting the ammeter to point Y is disconnected fromthe circuit. It is re-connected to a jockey and placed along the potentiometer wire.

At point Z on the potentiometer wire, the ammeter reading registers zero reading.

(i) Calculate the new potential difference VXYacross the potentiometer wire.

VXY= V

[1]

(ii) Given that the balanced length of potentiometer wire lXZis 0.450 m, find theunknown e.m.f E.

E= V [3]

Fig. 4.2


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5 The controlled reaction between deuterium ( 21H) and tritium ( 3

1H) has involved going

research for many years. The reaction can be summarized as

2

1H + 3

1H 4

2He + 1

0n + Q

where Q= 17.7 MeV.

Binding energies per nucleon are shown in Fig. 5.1.

Binding energy pernucleon/MeV

2

1H 1.12

1

0n -

4

2He 7.07

Fig. 5.1

(a) Suggest why binding energy per nucleon for the neutron is not quoted

[2]

(b) Calculate the mass defect, in kg, of a helium 42He nucleus.

mass defect = kg [3]

(c) (i) State the name of the type of reaction illustrated by this nuclear equation.

[1]

(ii) Determine the binding energy per nucleon, in MeV, of tritium ( 31H).

Binding energy per nucleon = MeV [3]


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8

Section B

Answer twoquestions for this section. Each question carries 20 marks.It is recommended that you spend about one hour on this section.

6 (a) Two long straight vertical wires X and Y pass through a horizontal card, as shown inFig. 6.1.

The current in each wire is in the upward direction.

The top view of the card, seen by looking vertically downwards at the card, is shown inFig. 6.2.

(i) Define magnetic flux density.

[2]

(ii) Draw four field lines in Fig. 6.2 to represent the pattern of the magnetic fieldaround wire X due solely to the current in wire X,

[2]

Fig. 6.1

Fig. 6.2


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(iii) Draw an arrow in Fig. 6.2 to show the direction of the force on wire Y due tothe magnetic field of wire X.

[1]

(iv) The magnetic flux density B at a distancex from a long straight wire due to a

current I in the wire is given by the expression

where mois the permeability of free space.The current in wire X is 5.0 A and that in wire Y is 7.0 A. The separation of thewires is 2.5 cm.

1. Calculate the force per unit length on wire Y due to the current in wire X.

force per unit length = N m-1 [3]

2. The currents in the wires are not equal.State and explain whether the forces on the two wires are equal in magnitude.

[2]

(b) Fig. 6.3 shows a metal rod PQ of mass 6.0 g rolling freely down a slope at a constant

speed von two parallel, frictionless metal rails separated by a distance of 90 cm. Aresistor of resistance 2.0 W is connected across the two rails such that a constantcurrent flows through it. You may assume that the rod and the rails have negligibleresistance.

The slope makes an angle of 20o to floor. A vertical uniform magnetic field of fluxdensity 180 mT is acting upwards in that region.

Fig. 6.3

20o

2.0 W

v

90 cm

metal rod

metal rails

magnetic field

P

Q


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(i) State Faradays law of electromagnetic induction.

[2]

(ii) Deduce the direction1. of the induced current.

[1]

2. of the corresponding electromagnetic force acting on the rod.

[1]

(iii) As the rod slides down the frictionless rails at a constant velocity, there arethree forces acting on the rod: the normal contact force Ndue to the rails, theelectromagnetic force Fand the gravitational force W.

On the free-body diagram of the rod in Fig. 6.4, indicate and label these threeforces clearly, taking into account their relative strengths and directions.

[2]

(iv) Show that the current flowing through the 2.0 Wresistor is about 0.13 A.

[4]

20o Fig. 6.4


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7 (a) Discuss how interferenceand diffractioncontribute to the action of a diffractiongrating.

[3]

(b) A parallel beam of red light of wavelength 6.3 10 7m from a laser is incidentnormally on a diffraction grating as shown in Fig. 7.1

The diffraction grating has 300 lines per millimetre.

(i) Calculate the separation d between adjacent lines of the grating. .

separation d= m [1]

Fig. 7.1


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(ii) Calculate the angle q at which the first order red spot is seen. This is thefirst spot away from the straight through position.

q =o [3]

(c) Calculate

(i) the energy of each photon of light emitted by the laser at a wavelength of6.3 10 7m.

energy = J [2]

(ii) the number of photons emitted each second to produce a power of 0.50 mW.

number = [3]

(d) (i) A beam of electrons in a vacuum can travel through a thin sheet of graphiteperpendicular to the beam to produce a diffraction pattern of rings on afluorescent screen beyond the graphite sheet. Explain why this pattern isproduced.

[3]


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(i) Calculate

1. the speed v of electrons with a de Broglie wavelength of 5.0 10-11m.

speedv= m s-1 [2]

2. the potential difference V required to accelerate the electrons to thisspeed.v.

p.d.V = V [3]


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8 (a) Fig. 8.1 shows how X-rays are produced inside an X-ray tube. The electrons, emittedat the filament, are accelerated from rest by an accelerating voltage of 10 kV to hit atarget of heavy metal at the anode and as a result X-rays are produced.

The spectrum of the X-ray beam shows that there are some very intense andsharply defined wavelengths superimposed on the continuous spectrum. Explainthe production mechanism of X-rays in the continuous spectrum and the emissionline spectrum.

[4]

Fig. 8.1

10 kV


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(b) A clean magnesium plate is placed in an evacuated glass container and illuminated withultra-violet radiation of wavelength 250 nm, as shown in Fig. 8.2. Another metal plate isat the opposite end of the container and the two plates are connected through amicroammeter to a variable d.c. supply. The polarity of the variable d.c. supply can bereversed.

Due to photoelectric effect, a current is registered by the microammeter.

(i) State what is meant byphotoelectric effect.

[1]

(ii) Calculate the photon energy, in eV, of the ultra-violet radiation.

energy = eV [2]

(ii) The work function of magnesium is 3.69 eV. Calculate the maximum energy,in eV, of electrons emitted from the magnesium plate.

maximum energy = eV [2]

Fig. 8.2


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(iii) Sketch a graph on the axes of Fig 8.3 to show how the current I in themicroammeter will vary with the potential difference V between the two metalplates.

Fig. 8.3[3]

(iv) Add another line on your sketch graph to show the effect of reducing the intensityof the ultra-violet radiation. Label this line lower intensity . [2]

(c) The diagram in Fig. 8.4 shows five electron energy levels of an isolated atom.The ground state and the ionisation level are included.

(i) Explain what is meant by ionisation.

[1]

Fig. 8.4


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(ii) An electron with kinetic energy 2.6 10-18J collides inelastically with anelectron in the ground state.

State which energy levels may be occupied following this collision.

[1]

(iii) A photon of energy 2.6 10-18J is incident on an electron in the groundstate.

State and explain what would happen.

[2]

(iv) After a separate excitation process, level D is occupied.

Calculate the longest possible wavelength of electromagnetic radiationemitted as the atom de-excites.

wavelength = m [2]

Mock Prelim 2012 H2 Paper 3

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