# Waves Flashcards Preview

## Harris Academy N4 Physics > Waves > Flashcards

Flashcards in Waves Deck (64)
1
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.

2
Q

What is meant by the frequency of a wave?

A

The number of waves per second.

3
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.

4
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.
5
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.
6
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.

7
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.

8
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.

9
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.

10
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.

11
Q

What type of wave is a sound wave?

A

Longitudinal.

12
Q

What type of wave is a water wave?

A

Transverse.

13
Q

What type of wave is a microwave?

A

Transverse.

14
Q

Name a longitudinal wave.

A

Sound.

15
Q

Name 3 transverse waves.

A
• Microwave
• Infrared
• Visible light
• Ultraviolet
• X-rays
• Gamma rays
• Water waves
16
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
17
Q

Which member of the electromagnetic spectrum has the most energy?

A

Gamma radiation as it has the highest frequency

18
Q

State one detector of radio waves.

A

Aerial

19
Q

State one detector of microwaves.

A

Aerial

20
Q

State one detector of infrared

A
• photodiode
• phototransistor
21
Q

State one detector of visible light.

A
• Eye,
• photographic film
22
Q

State one detector of Ultraviolet light.

A
• Some chemicals glow or fluoresce under it
• photocells
23
Q

State one detector of X-rays

A

Photographic film

24
Q

State one detector of gamma radiation

A
• Photographic film
• GM Tube
• Bubble chamber
25
Q

State one source of radio waves.

A
• Transmitter
• Stars
26
Q

State one source of microwaves.

A
• Transmitter
• Magnetron
27
Q

State one source of infrared.

A
• Stars
• Lamps
• Flames
28
Q

State one source of visible light.

A
• The Sun
• Light bulbs
• Anything hot enough to glow
29
Q

State one source of ultraviolet light.

A
• Sun
• Special Lamps
30
Q

State one source of X-rays.

A
• Stars
• Nebula
31
Q

State one source of gamma radiation

A
• Stars
• Some radioactive substances (e.g. Cobalt 60)
32
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
33
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
34
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
35
Q

State one use for visible light.

A
• We use light to !
• 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.
36
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.
37
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.
38
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
39
Q

What is meant by the ‘normal’?

A

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

40
Q

What do waves transfer?

A

Energy

41
Q

Which wave property is illustrated in the diagram below?

A

The amplitude of a wave.

42
Q

Which wave property is illustrated below?

A

Wavelength

43
Q

In the diagram below, where is;

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

See diagram

44
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.

45
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.

46
Q

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

A

The light is refracted and produces a spectrum.

47
Q

What is the shape of a convex lens.

A

See image

48
Q

What is the shape of a concave lens?

A

See image

49
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.

50
Q

What effect does a concave lens have on light rays?

A

It causes them to diverge - by refraction of the light

51
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)

52
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)

53
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.

54
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.

55
Q

What is meant by the term refraction?

A

When light changes speed when it enters a new medium with a change in direction. (If the angle of incidence is not equal to 0O)

56
Q

State a hazard of gamma radiation.

A
• kills cells
• causes cancer
57
Q

How can you protect yourself from ultraviolet radiation?

A
• wear suncream / sunscreen
• cover up, wear sunglasses
• stay out of the midday sun / in the shade
58
Q

How do people working with X-Rays protect themselves?

A
• Stand behind lead lined screens
59
Q

What is meant by ultrasound?

A

Frequencies above 20 000Hz.

60
Q

State a use for ultrasound

A
• scanning unborn babies
• sonar to measure the depth of the sea or to find shoals of fish
• Echolocation used by bats and dolphins
• Treating kidney stones
61
Q

What unit is sound level measure in?

A

deciBels

62
Q

What can happen if you are over exposed to loud sound levels for a long time?

A
• Hearing loss
63
Q

How can people who work with loud sounds protect themselves?

A
• Wear ear defenders
• Wear ear plugs