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GCSE Physics > Topic 5: Light and Electromagnetic Spectrum > Flashcards

Topic 5: Light and Electromagnetic Spectrum Flashcards

1
Q

What is total internal reflection?

A

When light is completely reflected back at a boundary between two mediums and it occurs when light meets a less dense medium at an angle of incidence larger than the critical angle

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2
Q

What is the critical angle?

A

The angle of incidence which causes the angle of reflection to be 90 degrees

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3
Q

What determines the colour of visible light waves?

A

The wavelength and frequency of the light waves

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4
Q

What colour of visible light had the highest frequency?

A

Blue

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5
Q

What colour of visible light has the largest wavelength?

A

Red

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6
Q

What is specular reflection?

A

Rays are reflected from a smooth surface in a single direction

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7
Q

What is diffuse reflection?

A

Reflection from a rough surface which causes scattering

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8
Q

How does a red colour filter work?

A

A red filter absorbs all wavelengths of light other than those in red range of the spectrum and this means only red light passes through the filter

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9
Q

What is opaque?

A

Not see through

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10
Q

What governs the colour of an opaque object?

A

Different objects reflect different wavelengths of light by different amounts and the wavelength that are most strongly reflected determine the colour

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11
Q

What happens to the wavelengths of light that aren’t reflected by an opaque object?

A

Any wavelengths that aren’t reflected are absorbed by the object

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12
Q

What colour does an object appear if all wavelengths are reflected by equal amounts?

A

White

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13
Q

What colour does an object appear if all wavelengths are absorbed?

A

Black

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14
Q

What do all bodies emit and absorb?

A

Infrared radiation

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15
Q

What happens to the quantity of infrared radiation emitted by an object as temperature increases?

A

The hotter the object, the more infrared radiation it will emit

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16
Q

What happens to the type of radiation emitted by an object as temperature increases?

A

The hotter the body the shorter the wavelength of radiation released?

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17
Q

What is required for a body to be at a constant temperature?

A

The body would need to emit radiation at the same rate it absorbs it - it needs to radiate at the same average power that it absorbs

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18
Q

What distributes any emissions that depends on temperature?

A

Intensity and wavelength

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19
Q

What is meant by intensity?

A

The power transferred per unit area, a measure of the energy transferred by a wave

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20
Q

What will happen if the average power that a object radiates is less than absorbs?

A

The temperature of the object will decrease

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21
Q

What can be said about the rates of emission and absorption for a body increasing temperature?

A

The body is absorbing radiation faster than it’s emitting it

22
Q

What factors that affect the temperature of the Earth?

A

The Earths rate of absorption and emission of radiation and the amount of reflection of radiation into space

23
Q

How does the Earths atmosphere affect radiation?

A

The atmosphere largely absorbs or reflects radiation from the sun, preventing it from reaching Earth and some radiation, however is allowed to pass through and warms the earth

24
Q

What happens to the radiation emitted from the Earth?

A

It’s absorbed and re-emitted in all directions by greenhouse gases, resulting in the greenhouse effect which warms the earth

25
Q

What types of waves are electromagnetic waves?

A

Transverse

26
Q

What do electromagnetic waves transfer?

A

Energy

27
Q

What type of spectrum do electromagnetic waves form?

A

A continuous spectrum

28
Q

What is the order of the electromagnetic spectrum in order of increasing wavelength?

A

Gamma, x-ray, UV, visible, infrared, microwaves and radio

29
Q

What is the highest frequency electromagnetic wave?

A

Gamma waves

30
Q

What is the highest energy electromagnetic wave?

A

Gamma waves

31
Q

What properties are shared by all electromagnetic waves?

A

They are all transverse waves, travel at the same speed (3x10^8) and they can travel through a vacuum

32
Q

What range of frequencies of electromagnetic waves can be detected by the human eye?

A

400-700 nanometers

33
Q

How do the speeds of EM radiation differ in a vacuum and in air?

A

EM waves all travel at the same speed in a vacuum and in air

34
Q

What can happen when radiation strikes an object

A

It can be transmitted, reflected or absorbed

35
Q

What type of waves can be produced by oscillations in an electrical circuit?

A

Radio waves

36
Q

How can radio waves create an alternative current in a circuit?

A

When radio waves are absorbed, they can induce oscillation in a circuit with the same frequency as the wave themselves

37
Q

Where do gamma rays originate from?

A

They originated from changes in the nuclei of atoms

38
Q

What health effects can ultraviolet waves causes?

A

They can cause skin to age prematurely and increase the risk of developing skin cancer

39
Q

What health effects can x-rays and gamma rays cause?

A

They are ionising radiation so can cause mutations in genes and can lead to increased risk of developing various cancers

40
Q

What health effects can infrared rays cause?

A

burns to skin/tissues

41
Q

How does EM radiation affect electron arrangement in atoms?

A

Absorption or emission of EM radiation can cause electron arrangement to change

42
Q

How do atoms become ions?

A

By losing an outer electron

43
Q

What are the effects of body cells absorbing radiation?

A

Large amounts can damage cells, smaller amounts cause mutations, causing cells to divide rapidly which can lead to cancer

44
Q

What is the use of radio waves?

A

Communication because radio waves are long wavelengths and can travel long distances without losing quality

45
Q

What is the use of microwaves?

A

Cooking, as microwaves are absorbed by and heat fat/water in foods

46
Q

What is the use of infrared radiation?

A

Cooing food, infrared cameras and short range communications

47
Q

What is the use of visible radiation?

A

Illuminating and fibre optics as they reflect best in glass

48
Q

What is the use of UV radiation?

A

Sterilisation as it kills bacteria, energy efficient lamps as it radiates low heat but high energy and sun tanning

49
Q

What is the use of x-rays?

A

Medical imaging and treatment because they’re very high energy and can easily penetrate body tissues

50
Q

What is the use of gamma rays?

A

Medical treatment, such as radiotherapy in the treatment of cancer

51
Q

Which waves of EM spectrum are regarded as most dangerous?

A

Gamma and x-rays as they have the highest energy

GCSE Physics (13 decks)

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