AnsTopic 4 Waves test 11_12 answers

8/3/2019 AnsTopic 4 Waves test 11_12 answers

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AMERICAN ACADEMY LARNACA6PHYSICS: SEMESTER 2: TEST IAdvanced Level - ASUnit 2: Physics at Work: Topic 3 - Waves ,Time: 1 hour 20 minutesWrite your name hereI_surna_me __ ------'---IOthe_r+.I [Write the date here

Youmust haveScientific calculatorRuler

GRADE

Instructions Use black ink or ball-point pen (blacklhlue). Fill in the boxes at the top of this page with your names and the date. Answer all questions (there are 18 questions and 2 challenge i bonus questions). Answer the questions in the spaces provided - there may be more space than you need. In calculations you shoul-d show all the steps in your working, giving your answer at each-stage.Information The total mark for this paper is 77 (+ 13challenge / bonus marks). The marks for each question are shown in brackets - use this as-a guide as to-luno much time to spend

on each question; Questions labelled with an asterisk (*) before the number of the question, are ones where the quality

of your written communication will be assessed - you should take particular care with spelling,punctuation and grammar, as well as the clarity of expression, on these questions.

Questions with an asterisk (*) after the number of the question are challenge questions. They aremore searching and deeper and it is intended to challenge your knowledge and understanding ofphysics. They are bonus questions and you should attempt them only if you have time.

The list of data, formulae and relationships is provided separately. You may use a scientific calculator.Advice Read each question carefully before you start to answer it. Keep an eye on the time. Try to answer every question. Always check your answers.

Turn over


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- e 1 -(

. .. ... .. . ..

SECTION AAnswer ALL questions.

For questions 1-10, in Section A, select one answer from A to D and put a cross in the box I Z I .If you change your mind, put a line through the boxSnd then

mark your new answer with a cross I Z I . \1 A laser beam is directed at the surface of a smooth, calm pond as shown in the diagram.

NormalI Birdi,//'~

.. ..I .I .I.......ir

Water ...... .. : \ : : ,: : : ~ .I . .I . .: -~ . II v

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

. .. .. . ..... . . .. . . .~.

CrabFish

Pondweed

Which organisms could be illuminated by the laser light?

I ~ A The bird and the fish.0 B The crab and the pondweed.II 0 C The bird and the pondweed.0 D The crab and the fish.I (Total for Question 1 = 1 mark)

'" '3

II

.,


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r--~ "' ""'~~~ -"---""----~ -~ ---~~"'-~ "" '~~~~~.gr.-.. .. ..~ --~= -'7~~~"""",-"""""",.~~,,,.t : 1 Which of the following electromagnetic radiations has the lowest frequency?B~E

~~I

o A gammaB infrared

oo D X-rays

C ultraviolet., ;- I

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ~ ( ~ ~ o ~ t a = l ~ f ~ o r ~ Q ~ u ~ e ~ s t i = o ~ n ~ l = _ = ~ l ~ m ~ a = r k ~ ) L _ ~_ ~I~~f: ~Il,/!i~~~~~~

~3When light from -adistant star reaches us on Earth, its wavelength appears shifted~ towards the red end of the spectrum. This is because

A the distance travelled by each successive wave has increased.

IIII - - - - - - - - - - ~ ~ ~ - (Total for Qu-estion3=1 mark)i 4 - Two loudspeakers produce identical sounds of frequency 440 Hz which superpose toI produce a standing wave. Adjacent nodes a~e formed 0.75 m apart.Select the correct statement about the waves.

B the frequency of the light emitted has d-ecreased.o C the speed of the star has increased.o -D the star is emitting longer wavelengths.

o A The frequency heard is 880 Hz.


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-~-ri5I '

IIIIIIjIII1 - - - - - - - - - - - - - - - - - - - - - - - - - -11 " 1 A wave is diffracted as it passes through an opening in a barrier. The amount of

diffraction that the wave undergoes depends on both theIIII1 - - - - - _ - - _ _ - - - - - - - - -II

A longitudinal wave is moving along a spring. Two points on the spring are separatedby half a wavelength. The displacements at these points on the spring are alwayso A constant.o B in the same direction as each other.

C in opposite directions to each other. ,D in a direction at right angles to the direction of travel of the wave.(Total for Question 5= 1 mark)

6 The diagram represents shallow water waves of constant wavelength passing throughtwo small openings in a barrier.

----- CrestTrough

The statement which best describes the interference at point Pis:

o A It is constructive and causes a longer wavelength.B It is constructive and causes an increase in amplitude.o C It is destructi,:e and causes a shorter wavelength.o D It is destructive and causes a decrease in amplitude.

________ --->(_Totalor Ques~ion - 6 =1 mark)

oo

A amplitude and frequency of the incident wave.B wavelength and amplitude of the incident wave.C wavelength of the incident wave and the size of the opening.

o D amplitude of the incident wave and the size of the opening.__!()tal for Question 1 - =1 mark)

\


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-5-3 A stationary observer hears a sound emitted by a moving source.

This produces a Doppler effect which is ao A change in frequency of the sound emitted by the source.~ B change in frequency of the sound heard by the observer.o C change in velocity of the sound emitted by the source.o D change in velocity of the sound heard by the observer.

(Total for Question g=1 mark)9 The diagram shows an experiment set up to demonstrate two-source interference, using

microwaves of wavelength A .

p

_k )-1 MicrowavedetectorMicrowavetransmitterThe detector is moved from 0 in the direction of the upwards arrow. The first positionwhere the signal is a minimum is P.The equation that correctly determines the position of P is

[J A OP=A~ B OP=A /2o C s. P-- ST::P=Ao D - S 1 P - S 2 P =A I2

(Total fo -r Question ?= 1 mark)


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-t;-riI /0 The diagram represents straight wavefronts passing across a boundary from deep waterI into shallow water, with a change in speed and direction.IIIIIIIIIII

Deepwater

BoundaryWhich wave property does this diagram illustrate?o A -diffractiono B . interferenceo C reflection

-~ .D refraction(Total for Question 10 = 1 mark)

TOTAL FOR SECTION A - 10 MARKS

I

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~li~~I' ; i!~iH J~~~~l~I~t , ( . it~tJ JII~~~~.............................._ _ s~. I~~m -~~I F '~"~~; .;


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-8-

/~\a) Refractometers are used in the food manufacturing industry to measure the~ concentration of sugar in different drinks. As the concentration of sugar increases,

the refractive index of the liquid also increases. A simple refractometer uses ahollow prism shape that can be filled with different liquids.(i) The simplified diagram below shows a ray of light passing through a prism

filled with a liquid. \

The liquid is replaced with one of a higher sugar concentration.Using the same incident ray, draw the new path through the liquid and out of thepnsm.

(2)(ii) In practice, a laser beam is shone through the empty prism. The position of

the emergent ray is marked on a screen. The .prism is filled with a liquid of aknown sugar concentration and the displacement on the screen is recorded.

Displacement.

LASERScreen


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r ~ "IIiIIIIiIIIIII .i . . .I!IIIII!IIIIIil

-fJ-This is repeated for a number of different known concentrations.The graph shows how the displacement varies with the sugar concentration.

110Displacement 100/ cm

908070605040

..Tt 1 '". . 1t+; "," . , , :

./-~ ./:,.

:/:. . , .

~. .. ..

o 20 40 60 80 100Sugar concentration / %

Describe how the displacement varies with sugar concentration.(2)

.; " J ~~~"'Y..~ ~ .

(iii) A sample of unknown concentration produced a displacement of 88 cm.Draw the line of best fit on the graph and use it to find the sugar concentrationof the sample.

Concentration = ......t:5..t

1IIIII


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IIirII : = ~ = t \ , ~ ; = ~ ~ = ~ m = ; ~ =i11Io~~ .w.-,\\~.\~~ ~~~b .i! ~ \ ~ ~ Q ~.~v.~~~~\A.>h1,~I ~ ~ . ~ . . . ~ . . \ ~ ~.~....~(P~\~ ~ yV\'1~II rI .IIi--Ii ?,~_~-=__~=mnm-=~.~.~~==~mmsm~~zmmEmmDE~~~~~~~~~~~~~~

-/0-

r! (iv) Give a reason why the distance between the screen and the prism must be keptconstant.

0)ck"':"y.~~~~\\.~ho ~ ~.$.~.~")~( ~.~.~~~~ ~ ~ ~.~ .

.......... -.~~~ .(b) Another method of measuring sugar concentrations uses polarised light.

(i) Explain what is meant by polarised light.(2)

*(ii) When polarised light passes through a sugar solution, the plane of polarisationrotates through an angle.Explain how to measure this angle of rotation.

(4)

(Total for Question I~= 13 marks)

I


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-//-/~ A girl is just able to hear sound from a point source when its intensity is1.0 x 1O-12Wm-2.

The girl is 455 m away from this point source of sound when she can just hear it.Calculate the power of the sound emitted by the point source.Give your answer to an appropriate number of significant figures. \. . . . . . .1 : 7 X ~ : . f . . . : : . .J.9 ..~.~Q~~~.~.~:-:~ ................~~~ ~ ~.~ ~ l4..~.~.~)~ .

(a)

~ - bpower of the sound ! . - : ~ xJ.Q W I(3 marks)

(b) The girl's father cannot hear the sound until its intensity is 1.0 x 10-6 Wm-2.(i) Calculate the ratio

amplitude of the sound wave just heard by the girlamplitude of the sound wave just heard by the father

. . . . . . . . . . . . . . . . . . . . . . ~ ~ ~ l : y .Q .> < . \ \ ! ~ ~ : .

. . . . . . . . . . . . . . . . . . . . . . .. .~ / . L ) ~:.?.~.. < ? . .

_ " lratio \9 . .(2 marks)

,(ii) With age, the father's hearing has become less sensitive to loudness.State one other change that will occur to the father's hearing as he ages .. . . . . . . .~~ 5.- .~~:~\~~ ~~ ~~.~~.0. I

I(1 mark) I @1


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-/.2-I~(a) Ultrasound scanning can be used by doctors to obtain information about the internal

structures of the human body without the need for surgery. Pulses of ultrasound aresent into the body from a transmitter placed on the skin.(i) The ultrasound used has a frequency of 4.5 MHz.

State why waves of this frequency are called ultrasound. \ (1)................................~~~ L..;.b~ ~ ~4. ..~~ .

(ii) A pulse of ultrasound enters the body and its reflection returns to the transmitterafter a total time of 1.6 x 10-4 S.Calculate how far the reflecting surface is below the skin.average speed of ultrasound in the body = 1500 m S-1

(3).. ...... ........ ...... .... ..... ...? Q .Q .~ '>~. ' 2 . J . . . . . .

\ 10 ~ to-~s....... ..... ....... .......... ............... , . , " " ... . . . . . . . . . . .. . .. . ~ ..~ t< ; .~ ..~.~.~\ ..lf \:..~ ..~.JQ~..~..~ .

"' LDistance = o . . . .rz ..~ .

(iii) State why the ultrasound is transmitted in pulses.(1)

.................................o. ~.V:.6 ~ ~ ~~.~~~ ..~~ ~ M..~ ........................;.~ ~~ \v. H.\.y~ ~ ~.~ ".


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-/3-(b) Another way of obtaining information about the internal structures of the human

body is by the use of X-rays.(i) Give one property of X-rays which makes them more hazardous to use than

ultrasound.(1)

............................\.o.~~~.\ ..~ .

(ii) State two other differences between X-rays and ultrasound.(2)

.......~.~~~ ~.~.s..~ ............~.~ .\~,~~.J..... : ...........~ ~~\~ .

(Total for Question / f -= 8 marks)


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

5j- ~

-/If.-

/5) Figure I shows a continuous progressive wave on a rope. There is a knot in the rope.Figure I

direction of wave motion)ope \equilibrium position

- - - - - - - - - - - - - - - - - - - - - - - - ~ - - - - - - - - - - -

-- (a) Define the amplitude of a wave............. _v.\!0-~~ .. ~\f!':..~4......

r - Q.. -\\. '.. . - h - - " .. . . . . . . . . . . . . ~


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--.---~-

-15-1 6 ) particledisplacement

film 54321 distance Im0-I

- 2- 2-4- 5

0.5 1.0 1.5

(a.) Explain what is meant by compression and rarefaction when applied to a sound wave .tra veiling in air. (2.)

(t; At this instant a compression occurs at B.(i ) Use the graph to explain how such a compression arises. (2.)( ii) On the graph indicate the positions of another compression and a rarefaction. (2)

(bJ

_ _ _ _ - " C A . . > . . . . ' ) f - - - - - " U 4 " L ) ~~~P>F="c.!:+ t1l .J" '-c :....:::.--=---..1. r(,.& i. o _ v \ .. .~ ~s..\.."Jl!',. "

\,)

______________~=~~~l~~~(~~~_~~Q __ , ~ .~~L~JL=-~k~-~NU~~~~~_~~j~hk~~/~----_' " ) L . . . ; \ ' , . . .\ - f 4 - = k lA b ~ L A ' : ) " = '- k,.Jl \ I,_ ~)c.. .19

Total for Question 16=6 marks... /16

., .


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~/6--1 & Waves on water are usually produced by wind blowing across the surface.Under certain conditions, standing waves called seiches can be produced on a shallow lake.

Antinodes occur at opposite ends of.the lake..Fig. 8.1 shows the cross-section of a lake where a seiche is occurring, at equal intervals of time.

t= 0 s

t= 24 s

~ .,;-{-----------:..=...::..:---~--~-"'~~~r--t = 48 s - 0 , .~ O J, s

< d O U oN--Fig. 8.1------p

(a) The standing waves shown in Fig. 8.1 occur in a small lake, 800 m long. They have a period of96s and amplitude of 1m.(i) Describe how someone viewing the lake might be aware that there were standing waveson the lake.

(it) For the standing wave, label each anti node A and each node N on thebottom diagram ofFig.8.1. .-:Use the labels to explain why the wavelength of the water waves is 1600 m.

[2]

[2]


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- q . -(iii) Explain why Fig. 8.1 shows that the period of the waves is 96 s.Use this to calculate the speed of water waves in the lake.-').\~ w :\\.. ~h.o ~\

. ltk~.J\

(c) In another lake, the longest period of seiche standing waves observed is about 14 hours,not 96s. Suggest and explain one way in which this other lake may differ from the one inFig.8.1.

[Total: 12]

[3]

[1]


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-/&-Ii)Adiagram shows the structure of a compact disc. A laser light beam is directed at right

angles to the underside of the disc.Reflective~--r-" layer

arentlayer

Beam oflaser light

The wavelength of the laser light in the transparent plastic layer is 414 nmrefractive index of the transparent plastic layer = 1.53(a) (i) Calculate the wavelength of the light in air.

(2). . ....... .... ......... . " .

If\ ~ b v ? '? A4'~ :;:;.,II\~r'?l~.> } > . - ; 4.\4....\~ .A.. .... ........... f .. .. .

Wavelength = b .. '1 "1 & 1 .~ .=(ii) Light reflected from point A is 1800out of phase with light reflected from point B.Calculate the minimum vertical distance from A to B.

(2)~~l = 4: l~tI\""................................................................t ~..~ .

Minimum vertical distance = J .9 . 1 : ' . . ~ ~ .


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---------------------------.--.-.-.-.--/?-

(iii) Explain the effect when the light reflected from A and B is combined.(2)

...................................~~~ ~\q:.~ .......................................u-h ~ ::: ~ .

- z . . . . . .

(b) Some of the reflected light will not hit the plastic-air boundary at 90.(i) Calculate the critical angle of the plastic-air boundary.

(2)............................\~ ~..~ \

V \.. -Critical angle = ,.~.o.:~~ , .-(ii) On the diagram below, show what happens to a ray of light which hits the

plastic-air boundary at point P at an angle greater than the critical angle.(2)

1_ I

~ 1. - - I ~ "._I~ ~ 1 . . . . ~ ' .

~: P - .. . ~ . PlasticT A i f

111111

. (Total for Question Ig = 10 marks)TOTAL FOR SECTION B = b-1MARKS

TOTAL FOR PAPER = 1=fMARKS


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-20-

[2]

w .

I i T ' A wave travelling along a string is represented by the equationy = 002 sin 2n:(4t + x)

where y is the transverse displacement at time t of a point on the string at a distance x from theorigin. All physical quantities are measured in SI units.(a) For this wave calculate: \. ~ ~ c ; : ' " ( - . v - l " "\ : : : . ) ( )

(i) the frequency; ,

[2 ]

........~ ..~..J..J\.~ :; ~J\ ?? ~..: < 6 . r . t : ; !t.~ .- =(ii) the wavelength; [2]

. . . . .. . .. . . ~ .. : ; ~ \ \ : 7 ~ \\ ~ J .. . . : : . : \ . ~ ~ ._ =A(iii) the speed.

(b ) Write down the equation of a wave of identical amplitude moving at the same speed and Ihaving the same wavelength as that given but moving in the opposite direction. [1]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. : : : : ~ . O :.Q .1 ~~ ~~.\!.f-t.~.~). , .

(Total for Question 19*= 7 marks)

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---------------------- ....21o / ~ 'to, .In a 'dolphinarium' (an aquarium in which dolphins are kept for show purposes)it.is noted that a characteristic dolphin sound of frequency 27kHz rises in tonewhen a dolphin approaches and drops in tone as the dolphin swims away.

(i) Explain why the sound frequency rises and falls. [2],(ii) A rise of 200 Hz' is noted as the dolphin swims towards the listener. Thespeed of sound in seawater is 1500 ID S-I. Calculate the speed of the dolphin. [4]

, ~----.-.. - .. -- '." 'X~ ~-l..- q') ,iI" ~' ':> C \ . r . . ) ~!1;) tr - \ -= CJ -- ) (c..- 'S " c . I

c- \l;. ~ C~-t.' = A "J . \ c . ~ -' t -'2.m1 \oh L'" -"~ ': A4--'-~ I~ r- 1-- \ > (t"\) '"'"'- -' \J. -:: C . \-+\\ = 7 \ ' - A . /. .

~ \ -\ p -!~,~1 =:: S < . T ' I ) o . . . ( c ; , -,= \\M~-' ~.

-

'*(Total for Question 20 =6 marks)

AnsTopic 4 Waves test 11_12 answers

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