# 15. P12 P13 Waves and EM Waves (Physics) Flashcards Preview

## SHHS - Science - Physics GCSE 2018on > 15. P12 P13 Waves and EM Waves (Physics) > Flashcards

Flashcards in 15. P12 P13 Waves and EM Waves (Physics) Deck (68)
1
Q

What is the law of reflection?

A

Angle of incidence(i) = Angle of reflection(r)

2
Q

What is a transverse wave?

A

The particle oscillations are perpendicular to the direction of the energy.

3
Q

Give examples of transverse waves.

A

light, water, radio, microwave, infrared, UV, X-rays, Gamma

4
Q

What is a longitudinal wave?

A

The particle oscillations are parallel to the direction of the energy.

5
Q

Give an example of a longitudinal wave.

A

Sound

6
Q

What is a wave?

A

A wave transfers energy and information from one place to another.

7
Q

Define Wavelength

A

The Wavelength is the length of one complete wave. (the distance between two corresponding points on a wave)

8
Q

Units of wavelength?

A

Metres (although can be measured in mm, cm or km)

9
Q

Define Amplitude

A

The amplitude is the maximum disturbance caused by a wave from its rest position. (centre line of wave up to the peak or down to the trough)

10
Q

Define frequency

A

The frequency is the number of waves passing a point every second.

11
Q

Units of frequency?

A

Hertz (or Hz - must be capital H)

12
Q

Define period (T)

A

The period is the time it takes for one complete wave to pass a point

13
Q

Units of time period (T) of a wave?

A

seconds, s

14
Q

Equation to calculate wave speed?

A

wavespeed = frequency x wavelength (v = f x ?) (? - lambda = wavelength)

15
Q

Equation to calculate time period of a wave from the frequency?

A

T = 1 / f

16
Q

In a longitudinal wave, the name given to areas where the particles are close together?

A

Compression

17
Q

In a longitudinal wave, the name given to areas where the particles are spread out?

A

Rarefaction

18
Q

What is refraction of waves?

A

The change in the direction of travel when a wave crosses a boundary between one medium to another due to the wave changing speed.

19
Q

Water waves refract when what causes the speed of the wave to change?

A

Depth of the water

20
Q

Light waves refract when what causes the speed of the wave to change?

A

Moves from one material to another of a different optical density.

21
Q

The line on a ray diagram that all angles are measured from during reflection or refraction?

A

normal

22
Q

How do you draw a normal line at the point the light strikes the mirror?

A

Normal line is drawn perpendicular to the surface at the point the ray strikes the surface (using a dashed line)

23
Q

What happens when a wave enters a glass block from air (not along the normal)?(Wavespeed, Angle, Wavelength and Frequency)

A

Wavespeed slows down, ray bends towards the normal, wavelength shortens , but frequency stays the same.

24
Q

What happens when a wave leaves a glass block from air (not along the normal)?(Wavespeed, Angle, Wavelength and Frequency)

A

Wavespeed speeds up, ray bends away from the normal, wavelength increases, frequency DOES NOT change.

25
Q

What are the properties of an image formed with a plane mirror?

A

Upright, Virtual, Laterally inverted, same size.

26
Q

What is the difference between a virtual and real image?

A

A real image can be formed on a screen where as a virtual image can be seen but does not actually exist.

27
Q

What is the speed of sound waves in air?

A

330m/s although it does vary with temperature.

28
Q

How does a sound change when the amplitude decreases?

A

Quieter

29
Q

How does a sound change when the Wavelength increases?

A

Lower pitch

30
Q

How does a sound change when the frequency increases?

A

Higher Pitch

31
Q

What is meant by ultrasound?

A

Sound waves with a frequency above 20,000Hz

32
Q

State the human hearing range for someone with perfect hearing.

A

20 to 20,000Hz

33
Q

What is meant by infrasound?

A

Sound waves below a frequency of 20Hz

34
Q

What state of matter is sound waves fastest in and why?

A

Solids, Particles are tightly packed.

35
Q

Give some medical uses of Ultrasound.

A

Prenatal scanning, blood flow meters, break up kidney stones, images of organs

36
Q

Give some industrial uses of Ultrasound.

A

Fishing boats scanning for fish, sea floor mapping, detecting flaws/cracks in steel

37
Q

Describe how bats use ultrasound.

A

Echo-location. For navigation and catching prey. The look for the reflection of the ultrasounds they emit.

38
Q

What is the name given to the exact point an earthquake occurs?

A

epicenter

39
Q

What are Primary (P-Waves) ?

A

Longitudinal waves that push or pull on material that they pass through. These cause the initial tremors.

40
Q

What are Seconday (S-Waves) ?

A

Slower moving transverse waves which shake material from side to side. These cause tremors a few minutes after p-waves.

41
Q

What are Long (L-Waves) ?

A

These travel the slowest, and only can travel through the Earth’s solid crust, causing violent movements up, down, backwards and forwards.

42
Q

State the four sections which make up the earth’s structure.

A

Crust, Mantle, Outer core and Inner core

43
Q

Describe the differences between p-waves and s-waves.

A

S-waves are Transverse, slower and can’t travel through liquids.

44
Q

Why can the s-waves not travel through the core of the earth?

A

Outer core is liquid, and s-waves can not pass through liquids.

45
Q

Describe what is meant by a mechanical wave.

A

A wave that requires a medium in which to travel i.e. water or a spring etc

46
Q

Describe what is meant by an electromagnetic wave.

A

Transverse waves that transfer energy by setting up electric and magnetic fields. Can travel through a vacuum.

47
Q

What is meant by the crest or peak of a wave?

A

The highest part of a transverse wave

48
Q

What is meant by the trough of a wave?

A

The lowest part of a transverse wave

49
Q

List the Electromagnetic waves in order from long to short wavelength

A

Radio, Microwave, Infrared, Visible, UV, X-ray and Gamma

50
Q

List the Electromagnetic waves in order from high to low frequency

A

Gamma, X-ray, UV, Visible, IR, Microwave, Radio

51
Q

State how a radiowave can be produced?

A

Oscillation in electrical circuits (vibration of charged particle such as electron)

52
Q

A

53
Q

State two uses of microwaves?

A

Heat food, mobile phones, Satelite tv, GPS

54
Q

State two uses of infrared?

A

heater, toaster, oven, treatment of muscle injuries, remote controls, infrared cameras

55
Q

State two uses of UV light?

A

Check for forged bank notes, sunbeds, investigating crime scenes, energy efficient lightbulbs.

56
Q

State two uses of X-rays?

A

airport security, check for broken bones

57
Q

State two uses of Gamma radiation?

A

Radiotherapy, sterilising surgical equipment, medical tracers, industrial tracers

58
Q

What are the two similarities of all electromagnetic waves?

A

All transverse, travel at the same speed in vacuum or air, transfer energy

59
Q

State the colours which make up visible light?

A

Red,Orange, Yellow, Green, Blue, Indigo and Violet.

60
Q

State a danger of UV light?

A

Ultraviolet waves can cause skin to age prematurely and increase the risk of skin cancer.

61
Q

State which types of EM waves are ionising radiation?

A

UV, X-ray and Gamma

62
Q

State what the effect on human tissue when they absorb Radio, Microwave, IR or visible?

A

Heating

63
Q

State what effect ionising radiation can have on human cells?

A

Can cause the mutation of genes and cancer.

64
Q

What two things do the effects of ionising radiation have on human body tissue depend on?

A

1) type of radiation and 2) the size of the dose.

65
Q

Radiation dose is measured in Sieverts, what is it a measure of?

A

It is the measure of the risk of harm resulting from an exposure of the body to the radiation.

66
Q

How many millisieverts are present in 5 sieverts of radiation dose?

A

5000millisieverts = 5 sieverts

67
Q

Which type of EM radiation can be used by fibre optic cables?

A

IR and visible light

68
Q

How are gamma rays generated?

A

Gamma rays are generated from changes within the nucleus of atoms.