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Physics CGP > Waves (Unfinished) > Flashcards

Waves (Unfinished) Flashcards

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1
Q

What type of waves are EM waves

A

Tansverse waves

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2
Q

EM waves characteristics

A

They travel at the same speed through a air vacume, they travel at the speed of light in a vacume, they travel slower in solids

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3
Q

Wave length of x-rays

A

10^-10 m

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4
Q

What happens to the wave length and frequency as you go down the EM spectrum

A

Increasing frequency and decreasing wavelength

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5
Q

Why is there such a large range of frequencies in EM wave spectrum

A

EM waves are generated by a variety of changes in atoms and their nuclei

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6
Q

Frequency of X-rays

A

10^17 hz

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7
Q

What is refraction

A

When waves crosses a boundary between materials at an angle it changes a direction

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8
Q

What effects refraction

A

How much the wave speeds up or slows down which usually depends on the density of the materials.

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9
Q

What directions do waves bend in refraction

A

If the wave slows down it will bend towards the normal

If it crosses into a material and speeds up it will bend away from the normal

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10
Q

What happens to the frequency when the wave length changes in refraction

A

It stays the same

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11
Q

What is the optical density

A

A measure of how quickly light can travel through, the higher the optical density, the slower light waves travel through it.

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12
Q

What does the angle of incidence always equal

A

the angle of refelction

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13
Q

How are radio waves made

A

By oscillating charges and magnetic fields

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14
Q

What does the frequency of the waves produced be eqaul to

A

The alternating current

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15
Q

What are radio waves used for

A

Mainly for communication

Long radio waves (1-10km) can be transported half way around the world.

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16
Q

How can short radio waves be transported long distances

A

Short radio waves (10-100m) can be recieved at long distances from the transmitter as they are reflected from the ionosphere.

Medium wave signals can also be reflected from the ionosphere depending on the atmospheric conditions

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17
Q

What type of video waves are used for TV and radio

A

Very short wavelengths

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18
Q

What are microwaves used for

A

Used by satalites for communication

Mircowave ovens

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19
Q

How does microwaves trasmitt from space

A

It’s signals on a transmitter is transmitted into space where it’s picked up by Saturday receiver dish orbiting and transmits the signal back to a satellite dish on the ground

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20
Q

How are microwaves used in the microwave ovens

A

Microwaves are absorbed by water molecules in food. The microwave penetrate after a few centimetres into the food little been dissolved and transfers energy to the carrying to the water molecules which then transfers the energy around

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21
Q

How can infrared radiation be used

A

To increase or monitor temperature

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22
Q

What can infared radiation be used for

A

Detect infrared radiation and monitor the temperature. The camera to text the IR radiation and turns it into an electrical signal

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23
Q

How can food be cooked by IR radiation

A

Absorbing IR radiation causes objects to get hotter

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24
Q

How was IR radiation used in electric heaters

A

Electric heaters contain a long piece of wire that heats up when a current flows through it. The wire that emits a lot of infrared radiation which is absorbed by objects in the air in the room, it is then transferred into thermal energy stores

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25
Q

How do fibre optic cables use visible light to transmit data

A

Optic fibres are thin glass or plastic fibres that can carry data every long distances as poses of visible light through reflection of the light rays about and forth until we reach the end of the fibre

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26
Q

How does ultraviolet radiation create flurocent lights

A

Fluorescent lights generate UV radiation which absorb and re-emitt as visible light by a layer compound called phosphor on the inside of the bulb.

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27
Q

How is UV radiation used in security pens

A

On the UV light the ink will blow if it is fluorescent but is invisible otherwise

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28
Q

How is UV radiation used for suntan

A

Ultraviolet radiation is produced by the Sun and exposure gives people a suntan, you can use UV lamps to give an artificial suntan however exposure can be dangerous

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29
Q

How are x-rays used in medicine

A

X-rays can be used by radio glasses to take photos to see bones or metal

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30
Q

How do x-rays work

A

X-rays pass easily through flesh but not through denser material like bones or metal.

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31
Q

How x-rays and gamma rays used in medicine

A

Radiographers use these raised to treat people with cancer good radiotherapy. This is because I doses of these rays kill a living cell so they are carefully directed towards cancer cells

32
Q

How is gamma radiation used as a medical traser

A

This is where a gamma emitting source is injected into a patient and its progress is followed around the body. Gama radiation is well suited as it can pass out through the body to be detected

33
Q

How can EM radiation be harmful

A

High frequency waves Such as UV rays x-rays and gamma rays or transfer lots of energy so can cause lots of damage. UV radiation damages surface cells which can lead to sunburn it can cause skin cancer. X-rays and gamma rays are types of ionising radiation which mutates or destroys cells and causes cancer

34
Q

What is ionising radiation

A

Radiation that produces from an ion as it has enough energy to displace an electron from an atom

35
Q

The speed of light speed

A

3.0 x 10^8 m/s in a vacuum.

36
Q

What does the particles of a medium do in waves traveling through a medium

A

The particles oscillate and transfer nergy between eachother

37
Q

What is the amplitude of a wave

A

The maximum displacement of a point on the wave from its undistured position

38
Q

What is a wavelength

A

The distance between the same point on two adjecent waves

39
Q

Wha is the frequency of a wave

A

The number of complete waves passing a certain point per second. It is measured in hertz

40
Q

What is the equation for a period (amount of time it takes for a full cycle) of a wave

A

Period = 1/frequency

41
Q

What are the characteristics of transverse waves

A

There are waves that have sideways vibrations. The oscillations are perpendicular to the direction of energy transfer. Less waves are transverse including electromagnetic waves, ripples and waves in water, a wave on a string.

42
Q

Longitudal waves

A

The oscillations are parallel to the direction of energy transfer. Some examples of sound waves in air, ultrasound or shockwaves

43
Q

Wave speed equation

A

Wave speed = frequency x wavelenght

44
Q

How can you use an oscilloscope to measure the speed of sound?

A

Set up the telescope to detect waves each microphone showing a separate waves. Start with both microphones next to the speaker then slowly move one away until the two waves are aligned on the display but have moved exactly one wavelength apart. That of the distance between the microphones to find one wavelength.You can use the equation to find the velocity from frequency and wavelength, The frequency is whatever you set the single generator to. The speed of sound in air is around 330 m/s

45
Q

What happens when waves arrive at a boundry betwen two different materials

A
  • the waves are absorbed by the material
  • the waves are transmitted often leadin gto refraction
  • the waves are reflected
46
Q

equation for angle of incidence

A

= angle of reflection

47
Q

What is the angle of incidence

A

The angle between the incoming wave and the normal

48
Q

What is the angle of reflection

A

The nalge between the reflected waveand the normal

49
Q

What is the normal line

A

An imaginary line that is perpendicular to the surface at the point of incindence

50
Q

What is specular reflection

A

Happens when waves is reflected in a single direction by smooth surface.

51
Q

What is diffuse reflection

A

When a wave is reflected by with surface and the reflected rays are scattered in lots of directions

52
Q

Why do diffuse rays scatter in different direction

A

The normal is different for each income in a way which means that angle of incidents is different for me to me

53
Q

How do different colours vary in characteristics

A

Each colour has its own narrow range of frequencies and wave lengths ranging from violets dow at the 400nm to reds at 700nm

54
Q

What do opaque objects do

A

They do not transmit light. When visible light waves hit them via the tube some wavelengths of light reflect others

55
Q

What does collour and transparency depend on

A

Absorbed wave lengths.

56
Q

Hat is ghe difference with black and white objects with light

A

White objects reflect

Black objects absorb

57
Q

What objects transmit light

A

Tranparent and translucent objects

58
Q

What is translucent and transparent colour depend on

A

Waves lengths of light transmitted and reflected by it

59
Q

What do colour filters do

A

Only let through particular wavelegths whch filter out different wavelegths of light so only some colours are transmitted - the rest are absorbed

60
Q

What happens to a colour if it is not the right colour filter

A

Any colour but the right colour looks black

61
Q

What is a perfect black body

A

An object that absorbs all of the rediation that hits it. No radiation is reflected or transmitted. They are the best possible emmitters

62
Q

What does the intensity and distribution of wavelengths emitted by an object depend on

A

The object’s temp (as the temp of an object increases the intensity of every emitted wavelegnth to decrease

63
Q

How do vibrations cause sound waves

A

Vibrations of an object are passes through the surrounding medium as a series of compressions and rarefractions

64
Q

What can humans hear in sound range

A

20 Hz to 20 kHz

65
Q

How can the ear hear sound

A

Vibrate. These vibrations are passed on to tiny bones in your ear called assistance through the semicircular canals to the cochela The tenancies vibrations into electrical signals which gets into the brain

66
Q

When would sound waves reflect and refract

A

Spund waves reflect by hard flat surfaces. Sound waves refract as they enter different media.

67
Q

What happens to sound waves in denser materials

A

The speed up because when a wave travels into different medium its wavelength changes is the same so the speed changes

68
Q

What iis ultra sound

A

Sound waves beyond the range of humans hearing higher than 20,000 Hz

69
Q

What is a partial reflection

A

When a wave passes from one medium to another some of the wave is reflected off the boundary between the two media and some is transmitted

70
Q

How is ultra sound useful

A

Medical imagining and industrial imaging

Ultrasound waves can enter materials or pass through a body

71
Q

How can you detect seismic waves

A

Earthquakes produces sismic waves which travel out through the earth. We can detect these waves usning sismometers to work out the time it takes for the shock waves to reach the seismetere.

72
Q

What is the movment of sismic waves through different layers

A

When seismic waves meet your country between different days of the material inside the Earth some waves as I will be reflected. Most of the time if the weather is affected the change in curved path. But when properties change suddenly the wave speed changes abruptly and the path as a kingk

73
Q

What are the two different seismic waves

A

P waves and S waves

74
Q

How can you use seismic waves

A

Bob serving outside affected scientists have been able to work out where the properties of the Earth changed. Our understanding of the internal structure of the Earth and size of that of course is based on observations

75
Q

P waves

A

Longitdal waves that move fast through solids and liquids and faster than s waves

76
Q

S waves

A

Are transverse and can’t travel through liquids

Physics CGP (7 decks)

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