Download pdf - Topic 4 Waves Student Workbook

7/24/2019 Topic 4 Waves Student Workbook

1/23

Name

Class..

IB Physics Topic 4. Waves

STUDENT WORKBOOK


2/23

Questions Worksheet #1 Introduction to SHM( /23)

ALL

1. Estimate the time periods of each of the following motions and hence calculate (to 1 sig.fig.) their

frequencies.

(a)child on a playground swing

period = .s [1]

frequency = Hz [1]

(b)a baby rocked in its mothers arms

period = .s [1]

frequency = Hz [1]

(c)the free swing of your leg from your hip

period = .s [1]

frequency = Hz [1]

[Total: 6]

2.The pendulum bob of a grandfather clock swings through an arc of length 196mm from end to end.

The period of the swing is 2.00 s.

(a)Explain what is meant by the period of the swing.

.. [2]

Continued on next page


3/23

(b)What is the amplitude of the swing?

Amplitude = m [1]

(c)What is the frequency of the bob?

Frequency = Unit [2]

3.What is (i)the frequency (ii)the period of:

(a)the rise and fall of the sea

i). Unit . [2]

ii). Unit [2]

(b)the beat of a heart

i). Unit . [2]

ii). Unit [2]

(c)piano strings which oscillate when middle C is played

i). Unit . [2]

ii). Unit [2]

[Total: 17]


4/23

Questions Worksheet #2 The Wave Equation( /38)

1 . (a) Define the following terms associated with waves.

(i)frequency,f

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

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

(ii) wavelength,

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

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

(b) Use the definitions in (a) to deduce an equation for the speed vof a wave in terms

of

and

f.

[3]

(c) (i) The speed of sound in air is about 340 m s1

while light travels at a speed of 3.0 108 m s

1.

Calculate the time interval between seeing a flash of lightning, 1.0 km away, and hearing the sound ofthunder caused by the lightning.

time interval = .................................... s [3]

(ii) Describe how observers may estimate their distance away from the point of a flash of lightning.

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

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

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



5/23

(d) State two differences, other than their speeds, between sound and light waves.

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

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

.................................................................................................................................................................. [2][Total: 11]

2. (a)Describe the differences between transverse and longitudinal waves.

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

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

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

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

(b)Fig. 3.1shows a progressive longitudinal wave formed in a slinky spring by an oscillatorconnected to a signal generator.

Fig. 3.1

OnFig. 3.1,

(i) draw arrows to show the direction of the vibrations produced by the oscillatorlabel these V. [1]

(ii) label with a C the centre of a compression on theslinky. [1]

(iii) show the wavelength of the wave and label this. [1]

(c) State and explain the effect on the wavelength of increasing the frequency of the oscillator.

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

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

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

[Total: 7]


6/23

3. Fig. 4.1shows a displacement-time graph for a wave source.

(a)Use Fig. 4.1to determine for this wave source

(i)the amplitude

amplitude = cm [1]

(ii)the displacement when t = 1.80 ms

displacement = cm [2]

(iii)the period

period = ms [1]

(iv)the frequency.

frequency = .Hz [2]


7/23

(b) The speed of the waves produced by this wave source is 3.0 102m s

1. Calculate their wavelength.

wavelength = m [2]

[Total: 8]

4. (a) (i) State what is meant by a progressive wave.

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

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

(ii) Describe in terms of the motions involved, the essential difference between longitudinal and

transverseprogressive waves.

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

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

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

(b) Describe how:

plane, transverse water waves can be produced in a ripple tank

the wavelength of these waves could be increased

the speed of these waves could be reduced.

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

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

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

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

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

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

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

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

.................................................................................................................................................................. [3]

[Total: 6]


8/23

5. Fig. 4.1 shows an incorrect electromagnetic spectrum drawn by a student. The parts of the spectrum

and the wavelengths are in the wrong order. The values of the wavelengths do not match the correct

parts of the spectrum.

(a)On Fig. 4.2, complete the table of the electromagnetic spectrum. Radio waves and their correct

wavelength have been inserted for you.

[3]

(b) State the speed of all electromagnetic waves in a vacuum.

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

(c) State two uses that are made of infra-red radiation.

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

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

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

[Total: 6]


9/23

Questions Worksheet # - Polarisation( /15)

1. (i) Define the termplane-polarisation of visible light waves.

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

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

(ii)Explain why sound waves cannot beplane-polarised.

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

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

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

[Total: 3]

2.Fig. 1shows a student observing a parallel beam of plane-polarised light that has passed

through a polarising filter.

Fig. 1

plane-polarised light polaroid

eye


10/23

(i)Fig. 2shows how the intensity of the light reaching the student varies as the polarising filter is

rotated through 360oin its own plane.

Suggest why there is a series of maximaandminimain the intensity.

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

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

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

(ii) Hence explain how sunglasses using polarising filters reduce glare.

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

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

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

[Total: 4]

intensity

00 90 180 270 360

angle of rotation


11/23

2. (a) Unpolarized lightis incident on the surface of a plastic. The angle of incidence is .

The reflected light is viewed through an analyser whose transmission axis is vertical.

The variation with of the intensity Iof the transmitted light is shown in the graph below.

(i)Explain why there is an angle of incidence, for which the intensity of the transmitted light is zero. [2]

(ii) Calculate the refractive index of the plastic.[2]


12/23

(b)Unpolarized light from a source is split, so that there is a path difference of half a wavelength

between the two beams

A lens brings the light to focus at point P on a screen. The lens does not introduce any additional path

difference.

State and explain whether any light would be observed at P, in the case in which the polarizers have their

transmission axes:

(i)parallel. [2]

Conti nued on next page.

(ii)at right angles to each other.[2]

[Total: 9]


13/23

Questions Worksheet # - Reflection & Refraction( /25)

1.Fig. 1.1shows a ray of light travelling from medium 1 to medium 2.

The speed of light in medium 1 is 3.0 x 108m s

1. The speed of light in medium 2 is 1.9 x 10

8m s

1.

(a) (i)Mark on Fig. 1.1the angle of incidencei. [1]

(ii)Show on Fig. 1.1the approximate path of the ray in medium 2. [1]

(b) (i)Calculate the refractive index for light passing from medium 1 to medium 2.

refractive index = ............................... [2]

(ii)Determine the value of i that corresponds to an angle of refraction, in medium 2, of 35.

i =............................... [2]

[Total: 6]


14/23

2. (a) Define the refractive indexof a transparent material. Identify any symbols used.

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

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

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

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

(b) Complete the table below by calculating the speed of light in water and the refractive index ofdiamond.

[3]



15/23

(c) Fig. 2.1shows a ray box and a rectangular glass block placed on a sheet of paper.

A ray of light enters the block and leaves from the other side as shown. The ray is laterally displaced

when it leaves the block.

(i) State why the ray is laterally displaced.

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

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

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

(ii) Explain why the emergent ray is parallel to the incident ray.

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

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

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


16/23

(iii)Describe how you would use the apparatus shown in Fig. 2.1to determine the refractive index of

the glass. Draw on Fig. 2.1, or in the space below, to help explain your answer.

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

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

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

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

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

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

[3]

[Total: 11]


17/23

3. (a) State two conditions necessary for light to be totally internally reflected.

1. ....................................................................................................................................................................

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

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

(b) Fig. 2.1 shows one end of an optic fibre used for data transmission.

The refractive index for the cladding/core interface is 1.01.

(i)Calculate the critical angle for the cladding/core interface.

critical angle = ............................... [2]

(ii)The fibre is to be used for data transmission. Explain why a large critical angle is needed and suggest

why a large critical angle results in a weak light pulse travelling down the core.

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

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

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

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

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

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

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

.................................................................................................................................................................. [4]

[Total: 8]


18/23

Questions Worksheet # - Wave Superposition( /25)

Fig. 6.1shows wavefronts incident on, and emerging from, a double slit arrangement.

The wavefronts represent successive crests of the wave. The line OX shows one direction along whichconstructive interference may be observed.

(a)State the principle of superposition.

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

................................................................................................................................................................... [3]


19/23

(b) On Fig. 6.1, draw lines to show:

(i) a second direction along which constructive interference may be observed (label this lineCC),

(ii) a direction along which destructive interference may be observed (label this line DD). [2]

(c) Light of wavelength 650 nm is incident normally on a double slit arrangement. The interference

fringes formed are viewed on a screen placed parallel to and 1.2 m from the plane of the double slit, asshown inFig. 6.2.

The fringe separation is 0.70 mm.

(i)Calculate the separation a of the slits.

separation = ................................. m [3]

(ii) The width of both slits is increased without changing their separation a. State the effect, if any, that

this change has on:

1. the separation of the fringes,

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

2. the brightness of the light fringes,

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

3. the brightness of the dark fringes.

................................................................................................................................................................ [3]

[Total: 11]


20/23

Questions Worksheet # - Standing Waves( /25)

1. (a) (i) State three phenomena that apply to all transverse and longitudinal waves.

1. ...................................................................................................................................................................

2. ...................................................................................................................................................................

3. ............................................................................................................................................................. [2]

(ii)State a wave phenomenon that applies to transverse waves only.

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

(b) Fig. 5.1 shows an arrangement that can be used to determine the wavelength of microwaves.

Microwaves leave the transmitter and move in a direction TP which is at right angles to the metal plate.

A standing (stationary) wave is formed between T and P.

(i)State what is meant by astanding waveand explain how it is formed in this case.

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

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

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

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

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

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

................................................................................................................................................................. [3]


21/23

(ii)When a small microwave detector D is moved slowly from T towards P the signal received changes

from strong to weak to strong to weak etc. The distance between the positions of neighbouring weak

signals is 1.4 cm.

Calculate for these microwaves:

1. the wavelength

wavelength = cm [1]

2. the frequency.

frequency = Hz [2]

(iii) Describe how you could test whether the microwaves leaving the transmitter were plane polarised.

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

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

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

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

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

[Total: 11]

OCR 2823/01 Jan p07


22/23

2. (a) In standing waves, there are nodes and antinodes. Explain what is meant by:

(i) a node,

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

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

(ii) an antinode.

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

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

(b)Fig. 5.1shows a long glass tube within which standing waves can be set up.

A vibrating tuning fork is placed above the glass tube and the length of the air column is adjusted, by

raising or lowering the tube in the water, until a loud sound is heard.

(i)The standing wave formed in the air column is the fundamental (the lowest frequency). Show on Fig.

5.1 the position of a nodelabel as N, and an antinodelabel as A. [2]

(ii)When the fundamental wave is heard, the length of the air column is 0.32 m.

Determine the wavelength of the standing wave formed.

wavelength = ..............................m [1]


23/23

(iii) The speed of sound in air is 330 m s1

. Calculate the frequency of the tuning fork.

frequency = ............................Hz [3]

[Total: 8]

3. A phenomenon associated with microwave ovens is the uneven heating of food. An internet website

gives the following explanation and the illustration shown in Fig. 5.1. Microwaves of a fixed frequency

are emitted in all directions from a source within the oven. The waves reflect off the metal walls so thatthe microwave radiation reaching any particular point arrives both directly and by reflection. The waves

interfere and set up standing waves. This produces the pattern of hot and cold zones observed in food

heated in the oven.

(a)State how the reflected microwaves set up standing (stationary) waves in the oven.

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

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

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

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

(b)Mark on Fig. 5.1the positions of two antinodeslabel these as A. [1]

(c)The frequency of the microwaves is 2.45 109Hz. Calculate the wavelength of the microwaves.

wavelength = ................................... m [3]

[Total: 6]