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.. j Pf-IY-S/C-S ON II-IE MOVE ,M,OCI<.. - B ttayks .' 8cJ 1i'm.t.: / h... -35 f{,'-n.. \

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Page 1: Mock Paper

.. j

Pf-IY-S/C-S ON II-IE MOVE

,M,OCI<.. - B

ttayks .' 8cJ

1i'm.t.: / h... -35 f{,'-n..

\

Page 2: Mock Paper

1.

2.

3.

/..{.

-ScC- TtOf\) - A

The initial charge on a capacitor is 10 ~c. The capacitor dis.charges through a resistance of 1.0 kQ. The ti~e constant fo~ the d1Sc~arge

. 't 's 10 ms Which of the followmg statements is correct . ClrcUl 1., ' .

A The capacitance is 10 ~F H The capacitor was charged to a pot~ntial difference ~f 10 V C The charge remaining on the capaCltor after 2.0 ms is 2.5 ~C D The initial current is 1.0 mA

Which of the following statements about an electric field is n ot correct?

A En~rgy is transferred when a charge moves along an equipotential

B Field lines sh ow the shape and direction of an electric fie ld C Energy is transferred when a charge moves along a field line D Field lines and equipotentials cross each other at right angles

An alpha particle moves in a uniform magnetic field of strength 2.0 T at 1.6 x 10 7 m S-1 perpendicular to the fi eld. The electronic charge is 1.6 x 10-19 C. Which of the following gives the force, in n ewtons, on the alpha particle?

A 1.0 x 10-11 B 5. 1 X 10-12 C 4.0 X 10-26 . D 2.0 X 10-26

When a charge of 30 ~C is moved between two pOints, M and N, in a uniform electric field, 150 III of work is done. The potential difference between M and N is

A OV B 0.2 V C5V D 4500 V

j

Page 3: Mock Paper

Section · 8

Answer all the questions.

1 Study the circuit in Fig. 1.1 .

3 V S

I 0 0 0--

4700/-lF

220Q

Fig.1.1

The switch S is closed to charge the capacitor. When the switch is opened the capacitor discharges through the resistor.

Here is a list of values:

1.4 x 10-2 2.1 X 10-2 1.0 1.4 2.1

Choose from the list the value that is closest to

(a) the time constant r of the circuit in seconds

value .... . ..... ......... .. s

(b) the charge in coulombs on the capacitor when at a p.d. of 3.0 V

value .. ......... .. ........ C

(c) the energy stored on the capacitor in joules when at a p.d. of 3.0 V

value .. .. .............. ... J

(d) the initial value of the current in ampere when the fully charged capacitor discharges through the res istor.

value ..... . .... ... . .... . A

Ifd~: [4]

2

Page 4: Mock Paper

;. 2 This question is about the use of electromagnetic induction to measure rotational speed.

insulated copper coil

pu lse counter

Fig. 12.1

iron core

spinning magnet

Fig. 12.1 shows a pulse counte r connected to an insulated copper coil wound around an iron core. The counter records the number of times that the emf across the coil goes from negative to positive in each second.

(a) (i) On Fig. 12.1, sketch a loop of magnetic flux wh ich passes through the iron core.

[1]

(ii) Suggest why the core is made of iron, a magnetic material.

[1]

(b) The graph of Fig. 12.2 shows how the emf across the copper coil changes with time.

emf

/ ,/ "

1\ / v "

\ +

/ \ II \ o

1\ / time

\~ / r--- ----

Fig. 12.2

3

- -- - ------- ---- -

Page 5: Mock Paper

(i) Explain the shape of the graph.

(ii) On Fig. 12.2, sketch how the flux linkage of the coil changes with time.

[2)

[1 ]

(iii) When the magnet spins at 30 revolutions per second, the amplitude of the emf across the 120 turn copper coil is 1.3 V.

Estimate the maximum flux in the core.

maximum flux = ...................... ..... Wb [2]

(c) The amplitude of the emf for a given rotational speed can be increased by using a stronger magnet which increases the flux density in the coil.

Describe and explain two other modifications to the device of Fig. 12.1 to increase the 3.mplitude of the emf for a given rotational speed.

[3]

(d) Explain why the core is made from thin iron sheets glued together rather than being solid iron.

[Total: 11:]

[Turn over

1.-4 I

Page 6: Mock Paper

3 This question is about the possibility of fusion between a tritium nucleus and a deuterium nucleus.

A tritium nucleus ~ H and a deuterium nucleus ~H approach each other along the same line with the same speed u.

~H u u ~H

- - - 881-----... " - - - 1t-OC----W - - -

Fig. 3.1

Each nucleus decelerates, comes to rest and then accelerates in the reverse direction.

(a) (i) By considering conservation of momentum, explain why both nuclei cannot come to rest at the same time .

................................................... .... ..... .. .. ...... ...................... ......................................... [IJ

(ii) When the nuclei are closest together they have the same velocity. Show that this velocity is u15.

[2]

(b) (i) Energy is conserved during the interaction.

.- --..::..

Write a word equation relating the initial energy of the two nuclei when they are far apart, to their energy when they are closest together. Your equation shou ld make clear the kind(s) of energy involved .

...... ... .. ..... ... ... ........ .................. .......................................................... ... .. .... .................. [1]

Page 7: Mock Paper

(ii) Show that the total initial kinetic energy of the two nuclei is equal to 4.18 x 10-27 u2 joule where u is in m S-1 .

(iii) The potential energy E of two charges 01 and 02 ' separated by a distance r is given by

°1 °2 E = -- EO = permittivity of free space

4TI EO r For ~H and ~ H to fuse, their separation must be no more than 1.50 x 10-15 m.

Calculate the minimum value of u for fusion to take place.

minimum value of u = ........ .. ...... .. .. ............. .. ............. m 8-1 [SJ

[Total : ·9]

[Turn over

6

Page 8: Mock Paper

4 Fig. 4.1 shows a square flat coi l uf insulated wire placed in a region of a uniform magnetic field of flux density B. The direction of the field is vertically out of the paper, The coil of side x has N turns.

< x )

, .. _ .. _----i ,

~I L

Fig.·U

(a) (i) Define the term magnetic flux.

(&{tiCf} of unii()ui'l 'nClflne!ic iield

(ii) Show that the magn~ti'G" fl6x lin~age of the coil in Fig . 4.1 is NBx2

[1 ]

(b) The coil of side x = 0.020 m is placed at position Y in Fig . 4.2 The ends of the 1250 turn coil are connected to a voltmeter. The coil moves sideways steadily through the region of magnetic field of flu x density 0.032 T at a speed of 0.1 0 m S·1 until it reaches position Z. The motion takes 10 s.

[Turn over

-:;

Page 9: Mock Paper

0.0 0.01 0.02 0.03 0.04 0,05 0.06 0.07 0.08 0,09 0.10 distance/m I ! ! I ! ! ! ! ! I I

O.020m ..;--.----

y

v

1---»-0.10 m S-l

coil position at t == 0

/

/ /

region of uniform magnetic field B = 0,032T

Fig. 4.2

z

v

coil position at t == LOs

(i) Show that the voltmeter reading as the coil enters the field region, after t = 0,20s, is 80 rnV, Explain your reasoning fully,

[2]

(ii) On Fig, 4,3, draw a graphbf the voltmeter reading against time for the motion of the coil from Y to Z, Label the y~ axis with a suitable scale, [:3]

q= 'C 11 Ii I .. ! : t"! [l Ii I iT ,TT, iIi I II i : H I

! , 'j 1 I I J ' : Tl~ J J I!

't "1 iT+-! i I. , ,,l

i j h Ii, ! .. ~ 1 i-

t "+1 ! II ! I I i Ii I:j ill i .J I , JI +- i j j II f· , , .. I

.. .. il \ ' j j L

I ' .. t I 1 r i I t voltmeter .. . .. iJ ' 1 i! ! 1 I

tis reading _L .L I I i 1'1. : I ... ! i , )

i·,L

O.8 ',I t ' I

° 0,2 0.4 rl I 0,6

, 1,0 i I

I " i': I .. , i ' i ;, ': , I i ' : i I

I : I: j . '-:- i : ! I' ' ' I .. T I Ii; ! II i i ~. 1 I ' :. + .1 ~! I I' ! i ' I ' I ;-r. J : i Ii t- .. . - ! I i I I .L I

I, IJ ' T I I I 1..1.

~1 i I Ii ! II t~·· ...

I I j+-

I i .. . I i·l. I

Fig. 4.3

[Tota!: 7]

Page 10: Mock Paper

5 A nitrogen atom is initially stationary at point P in Fig. 5.1 , midway between two large horizontal parallel plates in an evacuated chamber. The nitrogen atom becomes charged. There is an electric field between the plates. Ignore any effects of gravity.

T 600 V

Fig. 5.1

(a) The direction of the electric force on the nitrogen ion is vertically downwards. State with a reason the sign of the charge on the ion .

.... ... ................ ............... .... .. ...... ...... ... .. .. .. .... .. ...... .... ..... ............. .... ............................ ... [1]

(b) The voltage between the plates is 600 V. At the instant that the ion, charge 1.6 x 10- 19 C and mass 2.3 x 10-26 kg, reaches the lower plate, show that

(i) the kinetic energy of the ion is 4.8 x 10-17 J

[2]

(ii) the speed of the ion is 6.5 x 104 m S-1.

[2]

(c) The electric field strength between the plates is 4.0 x 104 N C-1 . Calcu!ate the separation of the plates.

separation = .. ............ .... .. .. .. .. .. .. . m [1]

! For j=xaminer'5

Use

Page 11: Mock Paper

(d) The ion passes through a hole in the lower plate at a speed of 6.5 x 104 m S-1. It enters a reg ion of uniform magnetic field of flux density 0.17 T perpendicularl y into the plane of Fig. 5.2.

t x x x x x x x x x x

x x x x x x x x x x

x x x x x x x x -------- magnetic field x x . Into the plane of

x x x x x x x x x x the paper

Fig. 5.2

(i) Sketch on Fig. 5.2 the semicircular path taken by the ion . [1]

(ii) Calculate how far from the hole the ion will collide with the plate. Use data from (b).

distance = ... ..... ...... .. .. ... .. .. m [3]

[Total: 10]

For Examiner's

Use

JCY '" [Turn over

Page 12: Mock Paper

6.~· This question is about the discharge of combinations of capacitors.

In Figs. 4.1 and 4.2, the capacitors are charged through a 10 kQ resistor from a 10 V d.c. supply when the switch S is connected to X. They discharge when the switch is moved to Y. The ammeters A1 , A2 , A3 and A4 monitor the currents in the circuits. Initially, the switch is connected to X and the capacitors are fully charged.

Fig. 4.1 Fig. 4.2

(a) State

(i) the voltage across each capacitor in Fig. 4.1 ............... .... .. .... .............. ... ... .... .. V [1]

(ii) the voltage across each capacitor in Fig. 4.2 .............................................. .. ... V [1]

(b) (i) Calculate the total charge stored in the circuit of Fig. 4.2 .

charge = ............................. C [.1.]

(ii) Explain why the total charge stored in the circuit of Fig. 4.1 is the same as in the circuit of Fig. 4.2 .

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

21

----- ----- -

IExa~~er's Use

Page 13: Mock Paper

(c) Fig. 4.3 shows how the reading 1 on ammeter A2 in the circuit of Fig. 4.1 varies with time t as the capacitors discharge, after the switch is moved from X to Y at t = O.

l i mA

1.0 t$~~ttpl~Ttt~~tt~lttltP~l+ ;, t: ~~~,

lttm1··-t· t·i~:·-·· ~-- - !-i-,-·-t··-iml~···~··· ~.- ~-1 tL~';'--~f~···1t+-I~i+~·1- ··~-· --· . :. _ .......... *~. - -~ ~·l·t~~· .. :~ o ··· 4:1- ·+··+·j ..

o 0.5 1.0 1.5 t l s 2.0

Fig. 4.3

(i) Describe how and explain why the reading on ammeter A1 varies, if at all, over the same time interval .

..... .............. ... ............ .... ......... ..... ..... ...... ......... .... .. .................... ...... ...... .... .. ........ ... [2J

(ii) Sketch curves on Fig . 4.3 to show how you expect the readings on ammeters A3 and A4 to vary with time from t = 0, when the switch is moved from X t? Y in Fig. 4.2. Label your curves A3 and A4 respectively. [3]

[Total: 10j

For Examinerls

Use

[Turn over

(2

Page 14: Mock Paper

The cyclotron and the synchrotron are two machines used to accelerate charged particles. Discuss the similarities and differences between these two machines.

Your answer should include

• the method of accelerating the charged particles • the synchronisation of the accelerating force with the particle motion • the method of maintaining the charged particles in a curved path • the energies which each machine is capable of imparting to the charged particles

(numerical values are not required) • the relative advantages of the two types of machine.

. . . . . . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . ... ... ... ...... ' .~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...... ' .......... .

J3

Page 15: Mock Paper

.. .. . .. ...... ... ...... .... . ... .... .. ... ........ ... ........ ..... .... ......... ...... ... ... ... ... ... .. . .. ........... ....... .... .. .. .. .. .. .. ...... .... .. ..

... .... ... ........ ... ... ..... .... .. .. ... ... .. ..... .... ....... ... .. .. .. ... .... ... ... .. .... .. .. .... ...... .... ... .. .. . . . .. . .. . .. . . .. .. . . .. . . . .... . .... . .. ..

.... ... ....... ... .. ....... .. .. ... .... ... .. .... .. ... ... ... ..... ... ... ....... ... ....

.. ..... ..... .. ... ... .... .... ...... ......... .......... .. ....... ... .. ........ ....... :::::::::::: :: ::: ... :::::.: .. ::.:: .. :.:: .. .......... .. ... ... ... .... .. .. . .... ..... ..... .... .. .... .... .

....... . .. ....... ...... ......... ... ..... ....... ..... .. ... ... ..... ... ... .... .. .. ...... . .... .. . . ... ...... .. . . . . .. ... ..

.. ... .. .. ..... ... ..H.. •••••••• · •

. H...· ·· .. ... ...... .. ...... ..

14

[Total: 6~l

[Turn over

Page 16: Mock Paper

t -

8'. This question is about measuring the momentum of alpha particles.

alpha particle source

region of uniform magnetic field

to vacuum pump

Fig.11.1

hole

tube

detector

Fig. 11.1 shows the arrangement of apparatus required. The region of uniform magnetic field extends for about 0.5 m.

(a) (I) On Fig. 11 .1, sketch the path of alpha particles as they go from the source to the detector. [1J

(ii) State why there must be a vacuum in the tube.

[1 ]

(b) In the region of uniform magnetic field the alpha particles follow a path which is part of a circle of radius r.

(i) State the angle between the direction of the magnetic field and the velocity of the alpha particles.

angle = ............ 0 [1J

(ii) The magnetic force on an alpha particle of charge q in a magnetic field of strength B provides the centripetal force for the motion along a circular path of radius r.

Show that the momentum p of the alpha particle is given by

p == 8qr.

[2J

/5

Page 17: Mock Paper

(c) The uniform magnetic field is provided by an electromagnet. The strength of the field is increased from zero in steps of 50 mT at intervals of one minute. The bar chart of Fig. 11.2 shows the corresponding readings from the detector.

detector count 40 I---+--j--­

per minute 30 1----\--+--

20 1---1---1---

10

o o 50 1 00 150 200 250 300 350 400

field strength/mT

Fig. 11.2

All of the alpha particles from the source have the same energy.

(i) Suggest why the detector gives a large reading at one particular field strength .

[1 ]

(ii) Suggest why the detector gives a reading for all field strengths.

[1]

(iii) Use data from Fig. 11.2 to calculate the momentum of the alpha particles from the source.

'.,..' .... ... '

r= 2.5m

q=3.2 x lO-19 C

Ib

momentum = .. .... .. ..... ..... .... ... kg m 8-i [2J

[Total: :9]

[Turn over

· <

Page 18: Mock Paper

9 (a) (i) Particle accelerators may be used to collide two protons. If the protons have sufficient speed such an event can produce more protons.

Explain why high-speed protons are necessa ry for the producti on of more protons .

•••• • •• •• • • • •••••• • •••••• •• • • < • ••• • • • • • • •••• ••• ••• •• • ••••••••••• •• •• • ••• • • • • • •••••• ••• •••••••••••

. . . .... . .. ... ... . . ..... ...... . .. . . .. .... .. . .. .. .. .. . . . . .... ... .. . ... . .. ..... . .. . ......... .. ... .

. . ... ........ .... . . . .. . . . ... .. . ... ........ . . . . ..... . ... . ........ ....... . . ......... . . . .... . ... . ..

...... .. . .. . ...... . . . ..... . . . ....... .. . ........... .. ................ . ...... . ....................

(I)

(ii) Whenever matter is created it is always accompanied by an equivalent quantity a/antimatter.

(iii)

What conservation laws does the statement in italic imply?

........ .. .. ... .. . ... . . .. . . ... . . ... . . . .. ... . . .... . . .. ............... .. . .. .......... ... ..

.. . . . .. ......... . .... . . . . ........... ......... . ........ . . . . .............. . ... . ... . . . .......... .

. ... . . .. . ... . . . ..... .. .... . . .. .... .. ................ . ... .. , . . .. . .. , . .. .. . . .

.. . ....... . . .. . . . ..... ... ........ . .. . .. . . ....... . .. . . . . .... . .. . . ...... . .

... .. ..... . . . .. .. . . . ........... . . . . ... . . .... . .. ......... .. . .. ... .. .. . . ... . ... .. . .... . ...... ... .

. ... ... .. ...... .. . . . . . . ... . .. .. .. . .. .. ......... . . .. . . . ... . . . . . . .. .. .... . . .......... .. . . ... . ... .

An electron encounters a positron. The rest mass of an electron and that of a positron is 0.000 55u.

Describe the outcome of the encounter.

Support your description with relevant calculations.

Jl

Page 19: Mock Paper

(b) Using the information in the table, deduce the quark composition of all rt' I . h equatIOn. pa IC es m t e

Quark Charge Strangeness u +2/3 0 d -1/3 0 s -113 1

p . . .... . . . . 0- .. . .. .... . . . .. .. . .. . . ...... :

K- ..... .... ... . .. .... ... . ... K + .. ....... ... ............ . KO

C2.)

(c) Complete the following nuclear equation showing the beta- ' d . oxvgen. mmus ecay of an Isotope of

-) x (: 1)

(rt) The ~r (omega minus), a particle with strangeness -3, was identified in 1964 in an experiment involving an interaction between a K- meson of strangeness -1 and a

proton.

Is the 0- particle a baryon or a meson? Give two reasons for your answer .

. .. . .. . .. . .. . . . .. ... .. . . ..... . . . .... . . . .. . ... . ... . .... . . ... . . . .. .. .. . ..... . .. . ..... . . .. .... . ..... . ...

... . . . . .. . . . . . . .. . . . .. . .. . . . . . . . .. . . . . .... . . . .......... . .. . .. . . . ... . .... . ............. . ...... . . . ..... . .....

. . ... . . . . .. . . . .. . . . .... . . . . . .. , ............ ... .............. .. . ... . .... . .. . . .. . ............ . ... . .. . . . . .. .

.. . .. , .. . . . . ..... . ...... . ... . .. . . . .. . ..... . . . .... . .. . . . ... . .. . . . . . . ...... . . . .. .... . . . ... . .. . ...... ... ... . . (2)

(lof~1 10)

iH£ END

/r;