# Waves Flashcards

1
Q

State one detector of radio waves.

A

Aerial

2
Q

What is the difference in the two waves shown below?

A

The bottom wave has a higher frequency. (Or the top wave has a lower frequency)

3
Q

What happens to the speed of light as it travels from air into glass?

A

The speed of light in glass is slower than the speed of light in air.

4
Q

In the diagram below, where is;

• the normal ?
• the angle of incidence?
• the angle or refraction?
A

See diagram

5
Q

What path will the ray of light take as it passes through the glass prism?

A

Light ray is refracted at air/glass boundary and glass/ air boundary. Both result in a change of direction.

As it enters the block the speed of the light decreases and it changes direction towards the normal.

As it leaves the block the speed of the light increases and it changes direction away from the normal.

6
Q

State one use for microwave radiation.

A
• Mobile phone communications
• Used to heat/cook food
• Microwaves in space are used by astronomers to learn about the structure of nearby galaxies, and our own Milky Way
• Microwaves are also used by fixed traffic
7
Q

State one use for radio waves.

A
• Aircraft and shipping bands
• Radio waves detected from space are used by astronomers to find out what objects are made from
8
Q

In the hills you can sometimes pick up a radio signal but not a television signal. Explain why this happens.

A

Radio waves are longer wavelengths than television waves.

Radio waves diffract more and can reach the receiver.

9
Q

State one use for visible light.

A
• We use light to see!
• Lasers are visible light and are used in Xbox, Playstation, Bluray player, DVD (where the light is reflected from the tiny pits in the disc, and the pattern is detected and translated into sound or data)
• Lasers also used in laser printers
• In aircraft weapon aiming systems.
10
Q

What happens when white light is shone through a triangular prism as shown?

A

The light is refracted and produces a spectrum.

11
Q

What is meant by refraction?

A

Refraction is the change of speed of light as it enters a different medium - often observed as a change in direction.

12
Q

What happens to a light ray as it travels from air into glass?

A

It will slow down and change direction towards the normal.

13
Q

State one source of radio waves.

A
• Transmitter
• Stars
14
Q

What is the shape of a convex lens.

A

See image

15
Q

What type of wave is a microwave?

A

Transverse.

16
Q

State one source of visible light.

A
• The Sun
• Light bulbs
• Anything hot enough to glow
17
Q

State one detector of infrared

A
• photodiode
• phototransistor
18
Q

State one detector of X-rays

A

Photographic film

19
Q

Describe how to measure the speed of sound using the equipment below.

A
• Make a loud sound to the left of the first microphone.
• When the sound reaches microphone one it starts the fast timer, when the sound reaches the second microphone this stops the timer.
• Measure the distance between the microphones using a metre stick.
• The speed is calculated from distance between the microphones divided by the time on fast timer.
20
Q

What is the difference in the two waves shown below?

A

The top wave has a bigger amplitude and so has more energy.

(Or the bottom wave has a smaller amplitude so has less energy)

21
Q

What is meant by the amplitude of a wave?

A

It is the distance from the centre of the wave to the crest or trough.

22
Q

State one source of gamma radiation

A
• Stars
• Some radioactive substances (e.g. Cobalt 60)
23
Q

State one use for X-rays.

A
• Create images of bones to detect breaks
• Create images of organs for diagnosis
• Security to scan luggage at airports
• Doctors can give patients a “Barium Meal”, which is a drink of Barium Sulphate. This will absorb X-rays, and so the patient’s intestines will show up clearly on a X-Ray image.
24
Q

State one detector of microwaves.

A

Aerial

25
Q

Why does a triangular prism produce a spectrum from white light?

A

Different frequencies/colours of light refract by different amounts.

26
Q

You are 5km away from a thunder storm. What reaches you first - the thunder or the lighning? Explain your answer.

A

The lightning. The speed of light is faster than the speed of sound.

27
Q

Which wave property is illustrated below?

A

Wavelength

28
Q

Which member of the electromagnetic spectrum has the most energy?

A

Gamma radiation as it has the highest frequency

29
Q

What is meant by diffraction?

A

It is the bending of waves round an object.

30
Q

Does a light ray always change direction when it undergoes refraction?

A

No.

31
Q

What effect does a concave lens have on light rays?

A

It causes them to diverge - by refraction of the light

32
Q

State one use for infrared radiation.

A
• Skin emits infrared light we can be seen in the dark by someone using night vision goggles.
• Astronomers use infrared to give extra information about space. Infrared light maps the dust between stars.
• Can be used to create thermograms which are used in medicine as a diagnostic tool for cancer, deep vein thrombosis(DVT), circulation problems (Reynaulds syndrome)
• Remote controls for TVs, DVD, Bluray players etc
• Physiotherapists use heat lamps to help heal sports injuries
33
Q

Name a longitudinal wave.

A

Sound.

34
Q

What is meant by the critical angle?

A

The angle of incidence that gives an angle of refraction of ninety degrees.

Red lines on diagram illustrate this.

35
Q

What is meant by the frequency of a wave?

A

The number of waves per second.

36
Q

What path will the ray of light take as it passes through the glass prism?

A

Light ray still experiences a change of speed - it is still refracted but no directional change.

37
Q

What is meant by the wavelength of a wave?

A

It is the distance from a point on one wave to the same point on the next.

38
Q

What is meant by a transverse wave?

A

A wave that vibrates at ninety degrees to the direction of travel. A transverse wave is a wave in which the motion of the medium is at right angles to the direction of the wave.

39
Q

What happens to a light ray as it travels from water into air?

A

It speeds up and changes direction away from the normal.

40
Q

What is the difference in the diffraction pattern in a long wavelength and a short wavelength passing an object?

A

The longer wavelength diffracts more.

41
Q

What type of wave is a water wave?

A

Transverse.

42
Q

What effect does a convex lens have on light rays?

A

The light rays converge to a focal point, by refraction of the light.

43
Q

State one use for ultraviolet radiation.

A
• UV lamp in a chip shops. (The UV attracts insects, which are electrocuted by high-voltage wires near the lamp - so they won’t land on the food and contaminate it.)
• Detecting forged bank notes in shops (security markings fluoresce under UV light)
• Hardening some dental fillings
• Night club lighting
• UV security pens to mark property
• Killing microbes – Sterilising surgical equipment, air in operating theatres
• Food and drug companies use UV lamps to sterilise products
• Used by the body to produce vitamin D
• Doctors can use it to treat Vitamin D deficiency, acne etc.
44
Q

What is the difference between real and apparent depth? Explain how this happens.

A

We think that the water is shallower than it actually is. (apparent depth)

This is because

• The light is refracted at the water/air boundary and changes direction away from the normal
• Our eyes/brain assume that light travels in straight lines.
45
Q

State one source of infrared.

A
• Stars
• Lamps
• Flames
46
Q

Will long or short wavelengths diffract more?

A

Lomg wavelengths diffract more.

47
Q

State one source of X-rays.

A
• Stars
• Nebula
48
Q

State one detector of Ultraviolet light.

A
• Some chemicals glow or fluoresce under it
• photocells
49
Q

Describe how to measure the speed of sound with two students using a clapper board, stop watch and trundle wheel.

A
• One student takes the clapperboard and stands still.
• The other students takes the stop watch and uses the trundle wheel to measure a set distance away.
• The first student shuts the clapper board.
• The other student starts the stop watch when they see the clapper shut and stops it when they hear the sound.
• Speed of sound is calculated by distance between the students divided by the time on stop watch.
50
Q

State one source of ultraviolet light.

A
• Sun
• Special Lamps
51
Q

What do waves transfer?

A

Energy

52
Q

What type of wave is a sound wave?

A

Longitudinal.

53
Q

What is meant by the ‘normal’?

A

An imaginary line drawn at ninety degrees to the surface that all angles are measured from.

54
Q

State one source of microwaves.

A
• Transmitter
• Magnetron
55
Q

You are 10km from a thunder storm. You count 15 seconds between seeing the lightning and hearing the thunder. How do you calculate how far away the storm is?

A

Use d = vt

Where v is the speed of sound.

t is 15 seconds.

56
Q

Name 3 transverse waves.

A
• Microwave
• Infrared
• Visible light
• Ultraviolet
• X-rays
• Gamma rays
• Water waves
57
Q

What effect is shown here?

A

Diffraction

58
Q

How does is the frequency of a wave related to it’s energy?

A

The higher the frequency the more energy the wave has.

59
Q

You are 10km from a thunder storm. You count 15 seconds between seeing the lightning and hearing the thunder. You repeat this after the next lightning strike, the time between the lightning and the thunder is now 10 seconds. What does this tell you?

A

The storm has moved closer to you.

60
Q

Name the members of the electromagnetic spectrum, from lowest to highest frequency.

A

(Ronald Mcdonald Is Very Ugly eXclaimed George)

• Microwave
• Infrared
• Visible Light
• Ultraviolet
• X-rays
61
Q

How does light travel through an optical fibre?

A

It travels by Total Internal Reflection

62
Q

What is meant by a longitudinal wave?

A

A wave that vibrates along the direction of travel.In a longitudinal wave, the motion of the medium is parallel to the direction of the wave.

63
Q

What is meant by the period of a wave?

A

The time it takes one wave to pass a point.

64
Q

Which colour of light is refracted most in a triangular prism when white light is shone through it?

A

Blue light

65
Q

What happens if light is shone onto a surface at an angle greater than the critical angle?

A

It is no longer refracted it is totally internally reflected.

66
Q

State one use for gamma radiation.

A
• Used as a tracer in medicine
• Used to treat cancer
• Sterilisation of operating instruments
• In industry, radioactive “tracer” substances can be put into pipes and machinery, then we can detect where the substances go.
• Gamma rays kill microbes, and are used to so that it will keep fresh for longer. This is known as “irradiated” food.
• Checking for cracks in aeroplane wings and joints
67
Q

Which colour of light is refracted least in a triangular prism when white light is shone through it?

A

Red light

68
Q

State one detector of visible light.

A
• Retina in the eye,
• photographic film
69
Q

What is the difference in the diffraction pattern produced by waves passing through a wide and a narrow gap? (Wavelength is the same)

A

The narrower the gap, the more diffraction that occurs.

70
Q

What is the shape of a concave lens?

A

See image

71
Q

Which wave property is illustrated in the diagram below?

A

The amplitude of a wave.

72
Q

State one detector of gamma radiation

A
• Photographic film
• GM Tube
• Bubble chamber