Centre Number 71 Candidate Number

8/14/2019 Centre Number 71 Candidate Number

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TIME

1 hour 30 minutes.

INSTRUCTIONS TO CANDIDATES

Write your Centre Number and Candidate Number in the spaces

provided at the top of this page.

Answer all seven questions.

Write your answers in the spaces provided in this question paper.

INFORMATION FOR CANDIDATES

The total mark for this paper is 90.Quality of written communication will be assessed in questions 2(a)(ii), (c)

and 4(b).

Figures in brackets printed down the right-hand side of pages indicate the

marks awarded to each question.

Your attention is drawn to the Data and Formulae Sheet which is

inside this question paper.

You may use an electronic calculator.

Question 7 contributes to the synoptic assessment requirement of the

Specification.

You are advised to spend about 55 minutes in answeringquestions 16, and about 35 minutes in answering question 7.

A2Y1S6 2663

ADVANCEDGeneral Certificate of Education

2006

Physics

Assessment Unit A2 1

assessing

Module 4: Energy, Oscillations and Fields

[A2Y11]

THURSDAY 1 JUNE, MORNING

A2Y11

For Examinersuse only

Question

Marks Number

1

2

3

4

5

6

7

TotalMarks

71

Centre Number

Candidate Number


2/26

A2Y1S6 2663 2 [Turn over

Examiner Only

Marks RemarkIf you need the values of physical constants to answer any questions in this

paper, they may be found on the Data and Formulae Sheet.

Answer all seven questions

1 (a) (i) State the principle of conservation of energy.

_____________________________________________________

__________________________________________________ [1]

(ii) Give a practical example of a case in which kinetic energy is

transformed into thermal energy (heat).

_____________________________________________________

_____________________________________________________

__________________________________________________ [1]

(b) A ball of mass 0.26 kg is held at rest above a vertical coiled spring of

spring constant k. (The spring constant is the constant of proportionality

in Hookes law.) Initially the bottom of the ball is 0.55 m above the top

of the uncompressed spring, as shown in Fig. 1.1.

Examiner Only

Marks Remark

0.55 m

0.15 m

Fig 1.1 Fig 1.2


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Examiner Only

Marks RemarkThe ball is then dropped so that it falls on to the spring, compressing

it by 0.15 m. Fig. 1.2 shows the spring at the instant of maximum

compression, when the ball is again at rest. In the calculations below,

air resistance can be neglected.

(i) Calculate the loss of gravitational potential energy of the ball

between the situations shown in Fig. 1.1 and Fig. 1.2.

Loss of gravitational potential energy = ___________ J [2]

(ii) State what has happened to this energy.

_____________________________________________________

__________________________________________________ [1]

(iii) Hence calculate the spring constant k.

k= ___________ N m1 [2]


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Examiner Only

Marks Remark2 In parts (a)(ii) and (c) of this question you should answer in

continuous prose. You will be assessed on the quality of your written

communication.

(a) The Formulae Sheet gives the following expression for the productpV

of the pressure and volume of a gas:

(i) State what the productNm in this equation represents.

__________________________________________________ [1]

(ii) The quantity is called the mean-square speed of the

molecules.

Explain, in words, how you would calculate the mean-square

speed from a set of values c1, c

2, c

3... of the speeds c of the

molecules.

_____________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________

__________________________________________________ [3]

pV Nm c= < >13

2


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Examiner Only

Marks Remark (b) The Formulae Sheet gives the following expression for the average

kinetic energy of a molecule:

Fig. 2.1 is a graph of the average kinetic energy of a molecule

against celsius temperature .

Obtain numerical values for the gradient and energy intercept of this

graph.

Gradient = ______________ J C1

Energy intercept = ______________ J [4]

0

0 /C

Ek/J

Fig. 2.1 (not to scale)

1

2

3

2

2m c kT < > =

/J


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Examiner Only

Marks Remark (c) One assumption of the kinetic theory is that the collisions of the

molecules of the gas with the walls of the container are perfectly

elastic.

Describe and explain what would happen to the gas if the collisions

were inelastic.

_________________________________________________________

_________________________________________________________

_________________________________________________________

______________________________________________________ [3]

Quality of written communication [1]


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BLANK PAGE

(Questions continue overleaf)


8/26

3 A person is swinging a ball on the end of a string so that it moves with

uniform angular velocity in a horizontal circle (Fig. 3.1).

Fig. 3.1

(a) Fig. 3.2 shows a plan view of the ball moving in its circular path.

Fig. 3.2

(i) On Fig. 3.2, mark the path the ball would follow if the string were

to break when the ball is at the position shown. [1]

(ii) The force acting on the ball as it moves in its circular path with

uniform angular velocity is said to be centripetal (towards thecentre of the circle). Explain why it must be in this direction.

_____________________________________________________

_____________________________________________________

_____________________________________________________

__________________________________________________ [1]


Examiner Only

Marks Remark


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Examiner Only

Marks Remark (b) The ball has mass 0.15 kg and moves in a circle of radius 0.60 m. It

makes 2.0 revolutions each second.

(i) Assume that the ball rotates with the string in the horizontal plane.

Calculate the tension Tin the string.

Tension = ________ N [2]

(ii) In fact, the weight Wof the ball makes it impossible for the string

to be horizontal. The real situation is sketched in Fig. 3.3.

Fig. 3.3

Assume that the horizontal component of the tension has the value

calculated in (b)(i). Determine the angle .

= ________ [3]


W

T


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Examiner Only

Marks Remark4 In part (b) of this question you should answer in the form of

short notes. You will be assessed on the quality of your written

communication.

(a) A body moves with simple harmonic motion in a straight line. During

this motion, the force on the body is proportional to the displacement

from the equilibrium position and is in the opposite direction to the

displacement.

Fig. 4.1

Fig. 4.1 is a graph of the acceleration a of the body as a function of its

displacementx from the equilibrium position.

(i) Explain how Fig. 4.1 shows that the force on the body is

proportional to the displacement of the body from the equilibrium

position, and that the force is in the opposite direction to the

displacement.

_____________________________________________________

_____________________________________________________

_____________________________________________________

__________________________________________________ [3]

246

10

5

10

246

5

0 2 4 6

a/m s2

x/mm


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Examiner Only

Marks Remark (ii) Use Fig. 4.1 to find the amplitude and period of the motion.

Amplitude = ___________ mm

Period = ___________ s [4]

(b) Write revision notes, suitable for this examination, on the subject of

Damping and Resonance. The Specification gives the guidance:

Descriptive treatment of frequency response, resonance and effect of

damping.

Bullet point notes, illustrated by sketches and/or graphs, will be

sufficient.

_________________________________________________________

_________________________________________________________

_________________________________________________________

_________________________________________________________

_________________________________________________________

_________________________________________________________

_________________________________________________________

_________________________________________________________

______________________________________________________ [5]

Quality of written communication [1]


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Examiner Only

Marks Remark5 A student, asked to explain what is meant by a field of force, gave the

answer

A field of force is an area where a unit charge experiences a force.

(a) Identify two errors, omissions or irrelevant details in the students

explanation.

1. _______________________________________________________

_________________________________________________________

2. _______________________________________________________

______________________________________________________ [2]

(b) It seems that the student may have been confusing the explanation of a

field of force with the definition of electric field strength.

Define electric field strength and state how the direction of the electric

field is obtained.

_________________________________________________________

_________________________________________________________

_________________________________________________________

______________________________________________________ [2]


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Examiner Only

Marks Remark

QUESTIONS CONTINUE ON PAGE 14A2Y1S6 2663 13 [Turn over[Turn over


1140E

10/4/06ES22

26

40/4/06GG

GG1130

12/3/06GGGG

A2Y1S6 2663 13 [Turn over[Turn over

BLANK PAGE

(Questions continue overleaf)


14/26


15/26


Examiner Only

Marks Remark (ii) The radius of the Earths orbit about the Sun is 1.50 1011 m.

Calculate the mass of the Sun.

Mass of Sun = ________ kg [3]


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Examiner Only

Marks Remark7 Data analysis question

This question contributes to the synoptic assessment requirements of

the Specification. In your answer, you will be expected to use the ideas

and skills of physics in the particular situations described.

You are advised to spend about 35 minutes in answering this question.

Work functions of metals

(a) Nearly ninety years ago Robert Millikan carried out classic

experiments which provided quantitative proof of Einsteins

photoelectric emission equation (which is quoted in your Data and

Formulae Sheet). A clean metal surface in an evacuated tube was

illuminated with monochromatic light. If the light was of a suitable

wavelength, photoelectrons were emitted. When these electrons reached

the collecting electrode and passed round the circuit, a measurable

photocurrentIwas produced. A stopping potential was applied to the

collecting electrode so that the photoelectrons were just prevented from

reaching the collector. Typical current-voltage (I-V) characteristics were

as shown in Fig. 7.1. These characteristics were obtained when the

metal was illuminated, separately, with light of wavelength 546 nm and

365 nm.

2.0 01.5 1.0 0.5 0.5 1.0

1

2

3

= 546 nm

= 365 nm

Fig. 7.1

I/A

V/V


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Examiner Only

Marks Remark (i) Fig. 7.2 shows part of a circuit which could be used to find the

stopping potential and measure it.

Fig. 7.2

Insert appropriate symbols to complete the circuit. This circuit

should include a potential divider. Make sure that the battery

symbol shows the correct polarity for obtaining the stopping

potential part of theI-Vcharacteristic. [4]

(ii) The two characteristics in Fig. 7.1 show steady values of

photocurrentI, that differ in value.

Suggest a reason why there might be this difference.

_____________________________________________________

_____________________________________________________

__________________________________________________ [1]


collector

clean metalsurface

radiation

insert battery

symbol here

label meter

appropriately


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Examiner Only

Marks Remark(iii) In another experiment the stopping potentials were measured to a

greater degree of precision than in this experiment. Table 7.1 gives

the values of the stopping potentials Vs

required when the metal

was illuminated by light of different wavelengths .

Table 7.1

/nm Vs/V hf/J

365 1.430

436 0.875

496 0.530

546 0.300

(1) To how many significant figures is the 0.300 V value of thestopping potential quoted?

_______________________________________________ [1]

(2) Show that a formula for converting wavelengths in nm tophoton energies hfin J is

Equation 7.1

[2]

(3) Use Equation 7.1 to convert the values ofin Table 7.1 tocorresponding values ofhf. Insert these values in the third

column of the Table. [2]

(iv) (1) You are to plot a graph ofVs

against hfon the graph grid of

Fig. 7.3. Label the horizontal axis, select a suitable scale,

plot the values from Table 7.1 and draw the best straight line

through the points. [5]

hf in J in nm( )=

( )

1 99 10 16.


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Examiner Only

Marks Remark

Fig. 7.3

(2) Find the gradient of your graph. Give an appropriate unit.

Gradient = ___________________

Unit: ___________________ [4]

(3) Read off the intercept on the hf-axis.

Intercept on hf-axis = ___________ J [1]

1.5

1.0

0.5

0

Vs/V


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Examiner Only

Marks Remark (v) The Einstein photoelectric equation is

Equation 7.2

The term represents the maximum kinetic energy of the

photoelectron. This quantity is measured using the stopping

potential, and is given by

Equation 7.3

(1) Making reference to Equation 7.2, explain how the work

function of the metal can be obtained from your graph.

__________________________________________________

__________________________________________________

Calculate its value in electron volts (eV).

Work function = ___________ eV [2]

(2) Making reference to Equations 7.2 and 7.3, state how the

elementary charge e is related to the gradient of your graph.

_______________________________________________ [1]

hf hf mv= +01

2max

1

2mvmax

mv1

2max2

2

2

eVs= s


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Examiner Only

Marks Remark (b) Another way of measuring the work function of a metal is to study

the thermionic emission from it. As the temperature of the metal is

increased, more and more electrons are emitted from it. This emission

is called the thermionic emission current, and the current per unit area

of the metal is the thermionic emission current density. The equation

giving the thermionic emission current densityJat a kelvin

temperature Tis

J=A0T2e /kT Equation 7.4

whereA0 is a constant, is the work function and kis the Boltzmannconstant. To obtain the work function, the current densityJis measured

at a number of temperatures T.

(i) A simplified picture of thermionic emission is to suppose that the

free electrons in the metal behave like the molecules of an ideal

gas.

Use this picture and the idea of the work function of a metal to

suggest why, as the temperature of the metal is raised, more and

more electrons are emitted from it.

_____________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________

__________________________________________________ [3]


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Examiner Only

Marks Remark (ii) (1) The emission current densityJis the current per unit surface

area of the emitter. State its unit.

Unit: _________________________ [1]

(2) State the unit, if any, of the quantity e /kT in Equation 7.4.

Unit: _________________________

Hence obtain the unit, if any, of the constantA0.

Unit: _________________________ [2]

(iii) It is possible to use a graphical method to find the value offroma set of values ofJand T.

(1) Equation 7.4 can be rewritten in the form

Equation 7.5

Take natural logarithms (logarithms to the base e) of both sides

ofEquation 7.5.

Equation in logarithmic form:

[1]

A2Y1S6 2663 22

J

TA

2 0= e

kT/

kT/

kT/


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Examiner Only

Marks Remark (2) Compare your equation in (b)(iii)(1) with the standard linear

form

y = mx + c

and hence state the axes you would use to obtain a linear graph

from which could be determined.

y-axis (vertical): __________________

x-axis (horizontal): __________________ [2]

(3) On Fig. 7.4, sketch the graph you would expect to obtain. [1]

Fig. 7.4

(4) State how you would use the graph to determine the value of.

__________________________________________________

__________________________________________________

__________________________________________________

_______________________________________________ [2]

THIS IS THE END OF THE QUESTION PAPER



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S 4/06 4000 302507(177)


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A2Y1S6 2663.02

GCE Physics (Advanced Subsidiary and Advanced)

Data and Formulae Sheet

Values of constants

speed of light in a vacuum c = 3.00 108 m s 1

permeability of a vacuum 0 = 4 107 H m1

permittivity of a vacuum 0 = 8.85 1012 F m1

1( = 8.99 109 F 1 m)40

elementary charge e = 1.60 1019 C

the Planck constant h = 6.63 1034 J s

unified atomic mass unit 1 u = 1.66 1027 kg

mass of electron me = 9.11 1031 kg

mass of proton mp = 1.67 1027 kg

molar gas constant R = 8.31 J K1 mol1

the Avogadro constant NA = 6.02 1023 mol1

the Boltzmann constant k= 1.38 1023 J K1

gravitational constant G = 6.67 1011 N m2 kg2

acceleration of free fall on

the Earths surfaceg = 9.81 m s2

electron volt 1 eV = 1.60 1019 J

A2Y11INS


26/26

Mechanics

Momentum-impulse mv mu = Ft

relation for a constant force

Power P = Fv

Conservation of 12

mv2 1

2mu

2 = Fs

energy for a constant force

Simple harmonic motion

Displacement x =x0 cos torx =x0 sin t

Velocity

Simple pendulum

Loaded helical spring

Medical physics

Sound intensity = 10 lg10(I/I0)

level/dB

Sound intensity = 10 lg10

(I2

/I1

)

difference/dB

Resolving power sin = /D

Waves

Two-slit interference = ay/d

Diffraction grating dsin = n

Light

Lens formula 1/ u + 1/v = 1/f

Stress and Strain

Hookes law F= kx

Strain energy E= x

(= 12

Fx = 12

kx2

if Hookes law is

obeyed)

Electricity

Potential divider Vout = R1Vin/(R1 + R2)

Thermal physics

Average kinetic 12

m = 32

kT

energy of a molecule

Kinetic theory pV= 13Nm

Capacitors

Capacitors in series

Capacitors in parallel C= C1 + C2 + C3

Time constant =RC

ElectromagnetismMagnetic flux density

due to current in

(i)i long straight

(i)i solenoid

(ii) long straight

(i)i conductor

Alternating currents

A.c. generator E=E0 sin t= BANsin t

Particles and photons

Radioactive decay A = NA = A0e

t

Half life t = 0.693/

Photoelectric effect 12 mv2max = hf hf0

de Broglie equation = h /p

Particle Physics

Nuclear radius r= r0A

v x x=

02 2

T l g= 2 /

T m k= 2 /B =

0NI

l

1 1 1 1

1 2 3C C C C = + +

12

13

USEFUL FORMULAE

The following equations may be useful in answering some of the questions in the examination:

B =0I

2a

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Centre Number 71 Candidate Number