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Physics - P1 > P1.5 Waves > Flashcards

P1.5 Waves Flashcards

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1
Q

What are the 2 types of wave?

A

Transverse or Longitudinal

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2
Q

Describe the oscillations in transverse waves

A

In transverse waves the oscillations are perpendicular to the direction of energy transfer

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3
Q

Describe the oscillations in longitudinal waves

A

In longitudinal waves the oscillations are parallel to the direction of energy transfer

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4
Q

What type of waves are electromagnetic waves?

A

transverse

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5
Q

What type of waves are longitudinal?

A

sound waves

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6
Q

Give some examples of mechanical waves

A

water waves, shock waves, waves on a rope

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7
Q

What type of wave are mechanical waves?

A

transverse or longitudinal

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8
Q

All types of electromagnetic waves travel at the ——– speed through a vacuume.

A

SAME

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9
Q

What sizes do wavelengths in the electromagnetic spectrum vary from?

A

about 10 to the -15 to more than 104 meters

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10
Q

What is the order of waves in the electromagnet spectrum, from long wave length to short wave length?

A

radio waves- Long wave length

microwaves

infrared waves

visible light

ultraviolet

Xrays

Gamma rays

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11
Q

What do longitudinal waves show areas of?

A

Compression and rarefaction

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12
Q

When do you see a clear reflection in the mirror?

A

When light travelling in the same direction reflects from an even surface so it is all reflected at the same angle

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13
Q

What is the law of reflection?

A

Angle of incidence = Angle of reflection

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14
Q

What is the normal?

A

A construction line perpendicular to the reflecting surface at the point of incidence

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15
Q

What is diffraction?

A

When waves bend round obstacles causing the waves to spread out.

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16
Q

What does the amount of detraction depend on?

A

the size of the gap relative to the wavelength of the wave

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17
Q

When does significant diffraction only occur?

A

When the wavelength of the wave is of the same order of magnitude (same size) as the size of the gap or obstacle.

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18
Q

Why is light hard to diffract?

A

As it has a vey small wavelength so needs a very small gap.

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19
Q

What is refraction?

A

When waves go through a new material, causing them to change direction

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20
Q

In refraction, when are waves not refracted ?

A

if waves travel along the normal.

To be refracted they need to meet the medium at an angle

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21
Q

What is the amplitude of a wave?

A

the displacement from the rest position to the crest.

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22
Q

What is the wavelength of a wave

A

The length of the full cycle of the wave

eg- from crest to crest

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23
Q

What is the frequency of a wave?

A

The number of complete waves passing a point per second

OR

The number of waves produced by a source each second

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24
Q

What do waves transfer?

A

energy

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25
Q

in the equation: speed= frequency x wavelength (v= f x y)

What are the units?

A

v , speed- m/s

f , frequency- Hz

y, wavelength- m

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26
Q

Describe the uses of radio waves

A

COMMUNICATION

  • Long wave length means the wave diffracts around the curved surface of the earth and around hills and into tunnels.
  • Used for TV and FM radio
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27
Q

Describe the uses of microwaves

A

SATELLITE COMMUNICATION and MOBILE PHONES

-Pass easily through atmosphere

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28
Q

What are some possible risks with mobile phones?

A

mobile uses microwaves to pick up signals.

Some wavelengths in microwaves are absorbed by water molecules and heat them up. If the water happens to be in your cells, they may become damaged.

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29
Q

What are some uses of infrared rays?

A

REMOTE CONTROLS and OPTIC FIBRES

-Remotes controls work by emitting different patterns of infrared rays to send different commands to an appliance.

30
Q

What 2 rays are used in optical fibres?

A

infrared and visible light.

signal is carried as pulses of light of infrared radiation and is reflected off the sides of a very narrow core from one end of the fibre to another.

31
Q

Describe some uses of visible light

A

PHOTOGRAPHY

32
Q

What causes sound?

A

soundwaves, causing vibrations in a medium

33
Q

Describe the speed of sound in different materils

A

fastest in solids

can not travel in a vacuum as there are no particles

34
Q

What is the pitch of a sound determined by?

A

its frequency (higher the frequency, higher the pitch)

35
Q

What is the loudness of a sound determined by?

A

its amplitude (the bigger the amplitude, the louder the sound)

36
Q

What are echoes?

A

reflections of sounds

37
Q

Describe the Doppler effect

A

When a wave source (light, sound or microwaves) moves away from an observer, the observed wavelength increases and the frequency decreases- lower pitch

When the source moves towards an observer, the observed wavelength decreases and the frequency increases.- higher pitch

38
Q

What is the Doppler effect?

A

If a wave source is moving relative to an observer, there will be a change in the observed wavelength and frequency

39
Q

Describe the theory of red shift and how it supports the Big Bang theory

A
  • Red shift shows galaxies are moving away.
  • More distant galaxies show a greater increase in wavelength so therefore a bigger redshift
  • More distant galaxies are moving away faster
  • This suggests that there was once a single point of origin
40
Q

What is the Big Bang theory?

A

That the universe began from a very small initial point

41
Q

What does CMBR stand for?

A

Cosmic Microwave Background Radiation

42
Q

What is CMBR?

A

a form of electromagnetic radiation which fills the universe. It comes from radiation that was present shortly after the beginning of the universe - now seen as microwave radiation

43
Q

How does the discovery of CMBR support the Big Bang theory?

A

The Big Bang theory is currently the only theory that can explain the existence of CMBR.

44
Q

What are some limitations with the Big Bang theory?

A
  • Some people still believe in other theories (steady state theory)
  • There are observations the theory can not explain
  • Does not explain what caused the explosion
45
Q

What are some properties that are the same for both radio and microwaves?

A

can be used for communication

travel at the same speed through a vacuum and air

transverse waves

can be reflected/diffracted/refracted/absorbed

transfer energy

46
Q

What is the property of microwaves that allows them to be used for satellite communications?

A

they can pass easily through the ionosphere

47
Q

What do scientists believe is the origin of CMBR?

A

the Big Bang

48
Q

How is the wave length of CMBR likely to change over the next billion years, why?

A

it is likely to increase

because the universe continues to accelerate outwards (expand)

49
Q

What type of image is formed when you see an objects reflection in a mirror?

A

Virtual

Upright

Laterally inverted

50
Q

Why is an image of a reflection virtual?

A

As the image is formed by virtual (imaginary) rays crossing

51
Q

What is a virtual image?

A

it cannot be formed on a screen

52
Q

What does it mean if the image formed in a mirror is laterally inverted?

A

left of the object seems to be on the right in the reflection

53
Q

How many Hz are in a KHz?

A

1000

54
Q

What happens when a metal arial absorbs radio waves?

A

an alternating current is created

with the same frequency as the radiowaves

the arial gets hotter

55
Q

Why would an xray telescope based on earth not be able to detect xrays emitted from distant stars?

A

As xrays cannot penetrate the atmosphere

56
Q

When considering the origin of the universe, what is difference between the ‘big bang theory’ and the ‘steady state’ theory?

A

Big bang theory- universe started at one point

Steady state theory- universe has no origin as it has always existed

57
Q

Why does red-shift provide evidence to support both the big bang theory and the steady state theory?

A

Red shift provides evidence that the universe is expanding

both theories use the idea that the universe is expanding

58
Q

Why are scientists keen to carry out research on theories about how the universe began?

A

to find evidence to support one or both of the theories

or

to find evidence to disprove one or both theories

59
Q

Why do scientists not know why the universe was created?

A

insufficient evidence

60
Q

Which type of electromagnetic wave has the shortest wave length?

A

Gamma

61
Q

State differences between an ultraviolet wave and a visible light wave

A

Ultraviolet has a higher frequency

Ultraviolet has a greater energy

Ultraviolet has a shorter wavelength

62
Q

What does red shift tell scientists about the direction most galaxies are moving?

A

away (from each other)

63
Q

What information can scientists find out about a galaxy when they measure the size of the red shift the galaxy produces?

A

The distance (from earth)

The speed the galaxy is moving

64
Q

What does the observation of redshift suggest is happening to the universe?

A

The universe is expanding

65
Q

Give examples of infrared waves being used for communication

A

remote controls

optical fibres

66
Q

Many scientists think that the Big Bang theory describes the….

A

origin of the universe

67
Q

The discovery of cosmic microwave background radiation was important as it….

A

provided more evidence to support the big bang theory

68
Q

What is is used to describe the wavelength of a planet or star moving closer to earth

A

blueshift

69
Q

What is the electromagnetic spectrum?

A

Electromagnetic radiations which cover a continuous range of wavelengths

70
Q

Explain why low emission mobile phones should be marked

A

allows people to easily identify lower risk phones

this allows people to make a more informed choice

71
Q

Which part of the electromagnetic spectrum provides energy to heat water?

A

infrared

Physics - P1 (5 decks)

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