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AQA Physics - Triple Science🪐⚛️🧠 > Topic 13 - Electromagnetic waves > Flashcards

Topic 13 - Electromagnetic waves Flashcards

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1
Q

What are carrier waves?

A

Waves used to carry any type of signal

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2
Q

What are charge-coupled devices?

A

An electronic device that creates an electronic signal from an optical image formed on the CCD’ array of pixels.

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3
Q

What is a contrast medium?

A

An X-ray absorbing substance used to fill a body so that the organ can be seen on a radiograph.

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4
Q

What is the electromagnetic spectrum?

A

The continuous spectrum of electromagnetic waves.

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5
Q

What is ionisation?

A

Any process in which atoms become charged.

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6
Q

What are microwaves?

A

Electromagnetic waves between infrared radiation and radio waves on the electromagnetic spectrum.

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7
Q

What is optical fibre?

A

Thin glass fibre used to transmit light signals.

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8
Q

What is a radiation dose?

A

The amount of ionising radiation a person receives.

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9
Q

What are radio waves?

A

Electromagnetic waves of wavelengths greater than 0.1m

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10
Q

What is ultraviolet (UV) radiation?

A

Electromagnetic waves between visible light and X-rays in the electromagnetic spectrum.

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11
Q

What is wave speed?

A

The distance travelled per second by a wave crest or trough.

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12
Q

What is white light?

A

Light that includes all colours of the spectrum.

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13
Q

What is transmission?

A

The movement of waves through a medium.

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14
Q

What is absorption?

A

The transfer of energy from a wave to a medium.

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15
Q

What is ionising?

A

When an atom becomes an ion.

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16
Q

Which type of radiation has the longest wavelength?

A

Radiowaves, around 10 to the 3 metres.

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17
Q

What type of radiation has around 10 to the -2 metres?

A

Microwaves.

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18
Q

Which type of radiation has around a 10 to the -5 wavelength?

A

Infrared radiation.

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19
Q

Which type of radiation has a wavelength around 0.5 x 10 to the -6?

A

Visible light.

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20
Q

What type of radiation has a wavelength of around 10 to the -8?

A

Ultraviolet radiation

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21
Q

What type of radiation has a wavelength of 10 to the -10 metres?

A

X-ray

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22
Q

What type of radiation has a wavelength of around 10 to the -12 metres?

A

Gamma rays

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23
Q

What is the equation for wave speed?

A

Wavelength x frequency

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24
Q

What perfect black body object?

A

An object that absorbs 100% of the electromagnetic waves.

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25
Q

What is a leslie cube?

A

A cube with sides of different rates of absorption.

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26
Q

What is an endoscope?

A

An instrument that can be introduced into a body to see its internal parts.

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27
Q

What is the ionosphere?

A

The layer of the atmosphere containing a high level of ions and free electrons. It can reflect radio waves.

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28
Q

What is radiotherapy?

A

The treatment of disease using X-rays or gamma rays.

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29
Q

What are medical tracers?

A

A radioactive isotope used to track the movement of substances around the body.

30
Q

What is sterilisation?

A

The process of making something free of a contaminant.

31
Q

What is a dose?

A

The amount of radiation of 1 joule of energy in each kg of bodymass.

32
Q

What are sieverts?

A

The amount of radiation measuring a dose (the unit).

33
Q

What is a dosimeter?

A

A device used to measure the dose of a given substance.

34
Q

How are sound waves produced?

A

An alternating current to an oscillator makes a carrier wave, a wave of constant frequency and amplitude.

The carrier wave and the electrical signal from the microphone are merged together. This is called modulation.

The modulated carrier waves are supplied to the transmitter. This will emit a radio signal due to the varying current supplied by the carrier wave.

35
Q

How are radio waves produced?

A

Radio waves are produced by passing an oscillating electric current through a long wire called an aerial.
The frequency of the radio wave produced is the same as the frequency of the oscillating current.

36
Q

What are optical fibres?

A

Thin glass fibres that transmit either light or infrared waves. The rays are totally internally reflected. There is a short wavelength for waves with a high amount of data, and since they disperse more randomly it needs to be contained in the cable.

37
Q

What happens as wavelength gets shorter?

A

-They can carry more information.
-Their range becomes shorter.
-They spread out less.

38
Q

Why are long wavelength waves used for long-range communications?

A

They disperse less and travel further, however they can store less data.

39
Q

What are the uses of UV?

A

UV radiation is widely used in industrial processes and in medical practices for killing bacteria, phototherapy and suntanning.

40
Q

What are the dangers of using UV?

A

UV exposure increases the risk of eye disease, if protection isn’t used.

41
Q

What do X-rays do?

A

-Detect bone fractures, abnormal masses.
-Detects pneumonia. injuries, foreign objects or dental problems.
-Detectimg elements in space and detecting supernovae.

42
Q

What are the issues with X-rays?

A

-Being exposed to X-rays can cause cancer many years or decades.
-This can caused vomiting, bleeding, fainting, hair loss and loss of skin and hair.
-Mutations in DNA, causing cancer.

43
Q

What do gamma rays do?

A

-Kill cancer cells
-Testing equipment
-Sterilising medical instruments

44
Q

How do medical professionals protect themselves from ionising X-rays?

A

-Stand behind a barrier or wear a vest
-Wear a dosimeter to see if the environment is safe.

45
Q

What is the order of the electromagnetic spectrum?

A

Radio waves

Microwaves

Infrared waves

Visible light

Ultraviolet rays

X-rays

Gamma rays.

46
Q

What wavelengths and frequencies do long-wave waves have?

A

Long wavelengths and low frequency

47
Q

What wavelengths and frequencies do short-wave waves?

A

They have very short wavelengths and high frequencies

48
Q

What is the equation for wave speed?

A

Wave speed = frequency x wavelength

49
Q

What does white light contain?

A

All of the colours of the visible spectrum.

50
Q

How do photographers use shades and colours of light?

A
  1. In a film camera, the light is focused by the camera lens onto a light-sensitive film, the film needs to be developed to see the image of the objects photographed.
  2. In a digital camera, the light is focused by the lens onto a sensor. This image has thousands of pixels.
51
Q

What two things are true about infrared radiation?

A

The hotter an object is, the more infrared radiation it emits.

Infrared radiation is absorbed by the skin and can burn or kill skin cells as it heats them up.

52
Q

Which devices use infrared radiation?

A

Optical fibres in communications systems. Infrared is absorbed less than visible light in the glass fibres.

Remote control handsets for TV and radio transmit signals carried by infrared. It can be produced easily.

Infrared scanners are used in medicine to detect it emitted from hot spots on the body. This
can show whether a tissue is unhealthy.

Infrared cameras can spot animals and humans in the dark.

Electric heaters and cookers use infrared radiation.

53
Q

What are microwaves used for?

A

For communications, as they can pass through the atmosphere and reach satelittes.

Ovens using microwaves heat food faster than ordinary ovens. The oven itself does not become hot, only the food.

54
Q

What are radio waves used for?

A

They can be used to carry radio, TV and mobile phone signals.

You can use them to connect a computer to other devices like with Bluetooth.

They can be hazardous because they can enter the body.

55
Q

Why are radio and microwaves waves used differently?

A

Shorter wavelengths can carry more information.

Some have a shorter range.

They spread out less.

56
Q

What are microwaves and radiowaves used for?

A

Microwaves are used to transmit messages to satelittes.

Radiowaves are used for TV broadcasting as they can carry more information than longer radio waves.

Radio waves of wavelengths from about 1 metre up to about 100m are used by local radio stations because their range is limited to the area round the transmitter.

Radio waves of wavelengths greater than 100m are used by national and international radio stations because they have a much longer range than shorter-wavelength radio waves.

57
Q

What is the risk of electromagneitc waves in mobile phones?

A

It emits radiation close to the brain, which could affect people’s brains. More research is necessary to prove a link or lack thereof.

58
Q

How is sound emitted and detected?

A

An oscillator supplies carrier waves to the transmitter.

The audio signal is supplied to the transmitter.

The modulated carrier waves from the transmitter are supplied to the aerial. The varying A.C. supplied causes it to emit radio waves that carry the audio signal.

When radio waves are absorbed, they induce an A.C. causing oscillations. This frequency matches that of the radio waves.

The receiver circuit separates the audio signal from the carrier waves. The audio is then supplied to a loudspeaker which sends out sound waves similar to the sound waves received by the microphone.

59
Q

How do optical fibres compare with micro and radio waves?

A

Optical waves carry much more information as light has a much shorter wavelength than radio waves and so can carry more pulses of waves.

Optical fibres are more secure because the signals stay in the fibre.

60
Q

What happens if you are exposed to UV rays?

A

They can cause blindness and it is harmful to the skin.

61
Q

What precautions should you take when exposed to UV rays?

A

Use sun cream.

Don’t be exposed to the sun for too long.

62
Q

How are X-rays and gamma rays similar?

A

They are on the short wavelength end of the electromagnetic spectrum.

They carry more energy per second than longer-wavelength electromagnetic waves.

63
Q

What differences are there between X-rays and Gamma-rays?

A

X-rays are produced when electrons moving at high speeds are stopped.

Gamma rays are produced by radioactive decay.

Gamma rays have shorter wavelengths than X-rays so they can penetrate more susbtances than X-rays.

64
Q

What are Gamma rays used for?

A

Killing bacteria, when fired at bacteria they can kill them, preventing contamination.

Killing cancer cells,by destroying tumours and not surrounding tissue by being aimed.

65
Q

Why can X-rays and gamma rays be dangerous?

A

They can ionise cells, by removing electrons, which may cause damage or mutation and potentially cancer.

66
Q

How are X-rays used to generate images of organs?

A

X-rays pass through the body.

They pass through soft tiasue but are absorbed by bones, teeth and metal objects that aren’t too thin. This makes a negative image of the bones.

An organ of soft tissue that can be filled with a substance is used as a contrast medium.

Lead plates between the tube and patient stops X-rays reaching other parts of the body.

A flat panel detector is a small screen containing a Charge-coupled-device, which convert X-rays into light.

67
Q

What is a charge-coupled device?

A

A device that converts X-rays into light.

68
Q

What is a contrast medium?

A

An organ consisting of soft tissue that can be filled with a substance.

69
Q

What does radiation does depend on?

A

They type of radiation used

How long the body is exposed to it

The energy per second absorbed by the body from the radiation

70
Q

What can X-ray therapy do?

A

It can destroy cancerous tumours in the body.

71
Q

What is different about X-rays used for therapy?

A

They carry much more energy than X-rays used in imaging to kill tumours.

AQA Physics - Triple Science🪐⚛️🧠 (30 decks)

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