EM Spectrum Flashcards

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1
Q

What are the two rules of reflection

A
  • Incident angle = reflection angle
  • Angles are always measured from the normal
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2
Q

What is the rule of refraction

A

If entering a denser material it bends towards the normal

If entering a low density material bends away from the normal

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3
Q

What is the incident ray

A

the angle of the entering ray

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4
Q

What is the reflected ray

A

the angle of the exiting ray

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5
Q

What is the normal line

A

Imagery line perpendicular to surface

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6
Q

What is total internal reflection

A

When light passes from a denser medium into a less dense medium and the angle of incidence is equal to the critical angle

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7
Q

What happens if the angle is equal to critical angle

A

Light passes along the boundary

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8
Q

What is specular reflection

A

On a smooth surface all light incident at the same angle exit at the same angle

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9
Q

What is diffuse reflection

A

Light hitting a rough surface - incident ray is reflected at many angles rathe than one angle

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10
Q

How do coloured filters work

A

All other colours are absorbed and only a certain colour is able to pass through

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11
Q

What is focal length

A

The distance between the lens and focal point

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12
Q

What is a focal point

A

Point where all horizontal rays meet after passing through a lens

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13
Q

What are concave used for

A

Spreads light waves outwards

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14
Q

What are convex lenses used for

A

Focuses light inwards

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15
Q

Where is a real image produced

A

Produces at the opposite side of the lens to the object

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16
Q

Where is a virtual images

A

Produces an image on the same side of the lens

17
Q

What are the three characteristics of all EM waves

A
  • Transfer energy
  • Transverse
  • Travel the same speed in a vacuum
18
Q

Which wave has the longest wavelength and lowest frequency

A

Radiowaves

19
Q

Which wave has the short wavelength and higher frequency

A

Gamma ray

20
Q

What are the properties of radiation with higher energy

A
  • Highly ionising
  • Harmful to cells and tissues
21
Q

Properties of radiation with lower energy

A
  • Useful for communications
  • Less harmful to humans
22
Q

What is the wavelength and frequency of the colour red

A
  • Longest wavelength
  • Lowest frequency and energy
23
Q

What is the wavelength and frequency of the colour violet

A
  • Shortest wavelength
  • Highest frequency and energy
24
Q

How do you achieve constant temperature

A

it needs to radiate the same average power that it absorbs

25
Q

How does temperature increase

A

if it absorbs more power than it emits

26
Q

How does temperature decrease

A

If it absorbs less power than it emits

27
Q

How is the temperature of the earth maintained

A
  • Short wavelength infra-red radiation from sun hits earth
  • Some reaches the surface some reflected
  • Energy is absorbed and re-emitted as longer IR radiation
  • Absorbed by the atmosphere (ozone) and keeps earth warm
28
Q

Danger of microwaves

A

Internal heating of body cells

29
Q

Dangers of infrared

A

Skin burns

30
Q

Dangers of UV

A

Damage to surface cells and eyes - leads to skin cancer

31
Q

Dangers of X-ray/Gamma waves

A

Mutation/ damage to cells in the body

32
Q

Uses of Radio waves

A

Communications and satellite transmission

33
Q

Uses of microwaves

A
  • Cooking
  • Communication
34
Q

Uses of infrared

A
  • Optic fibres
  • Thermal imaging
35
Q

Uses of Visible light

A

Vision

36
Q

Uses of UV

A
  • Security marking
  • Disinfecting water
37
Q

Uses of x-ray

A
  • Observe damage to metal
  • Used for medical scanners
38
Q

Uses for gamma

A
  • Sterilising food/Equipment
  • Treating cancer
39
Q

What can changes in atoms and nuclei cause

A

the nucleus to become unstable and create a radioactive atom.