Electromagnetic Spectrum Flashcards

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1
Q

light can be r______ and r_______

A

refracted and reflected

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2
Q

what is the law of reflection

A

angle of incidence = the angle reflection

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3
Q

how is the normal line drawn

A

90 degrees to the surface

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4
Q

what is refraction

A

the change in direction of a light ray that happens when it travels from one transparent material to another

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5
Q

what is the critical angle

A

the angle at which refraction becomes a reflection

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6
Q

what are 2 essential factors for the total internal refraction in fibre optic cables

A
  1. the cladding must have a smaller refractive index (lower density) than the core
  2. the wave must meet the boundary at an angle greater than the critical angle
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7
Q

what are the 2 types of reflection?

A

specular
diffuse

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8
Q

what is specular diffusion

A

occurs when waves are reflected off a smooth surface.

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9
Q

what is diffuse reflection

A

occurs when the surface is not smooth and the irregularities cause thee waves to be reflected at many different angles

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10
Q

what are the colours that visible light is split up into

A

red
orange
yellow
green
blue
indigo
violet

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11
Q

why does a green object appear green

A

it is based of how the atoms on its surface respond to the light being shone at them. a material will appear green as the atoms reflect green light and absorb all the others

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12
Q

what is a filter

A

something that lets through and transmits a colour while absorbing all the others

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13
Q

what is a lens

A

pieces of glass that bend/refract light

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14
Q

what are the 2 types of lenses

A

converging
diverging

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15
Q

how does the power of a lens affect it?

A

the higher the power of the lens the more it refracts light

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16
Q

what is the focal point

A

the point where a lens focuses light

17
Q

what are the parts of the EM spectrum in order of longest wavelength to shortest

A

radiowaves
microwaves
infrared
visible light
ultraviolet
x-rays
gamma-rays

18
Q

what are some key factors about all EM waves

A

all transverse waves
travel at the same speed in a vacuum
transfer energy

19
Q

what 4 things can happen to EM waves

A

reflected
refracted
transmitted
absorbed

20
Q

which 2 EM waves are used for communicating

A

Radiowaves
Microwaves

21
Q

how are radio waves used for communication

A

they are sent via aerial into the ionosphere where they are reflected towards earth and the receiving aerial

22
Q

how are microwaves used for communication?

A

sent towards the ionosphere where they are transmitted by it to a satellite that will shoot it back down towards earth where it is retransmitted by the ionosphere towards receiving aerial

23
Q

what affects the temperature of an object

A

how much temperature they absorb and how much they radiate

24
Q

what are 2 uses of radio waves

A

broadcasting radio and TV programmes
communicating with ships and satellites

25
Q

what are 2 uses of microwaves

A

used in mobile phones
used in cooking

26
Q

what is the danger of microwaves

A

they heat water so they can heat water inside our body and can damage/kill them

27
Q

what are 4 uses of infrared

A
  • used in thermal imaging
  • remote controls
  • used to send information along optical cables
  • used in security systems such as burglar alrmas
28
Q

what is the danger of infrared

A

too much infrared can cause skin burns

29
Q

what are the uses of visible light

A

allows us to see
photography

30
Q

what are 3 uses of ultraviolet

A
  • inside fluorescent lamps
  • used to detect forged banknote
  • disinfect water
31
Q

what is the danger of ultraviolet

A

UV is in sunlight and can damage skin such as sunburns
can also cause skin cancer over long exposure

32
Q

what are 2 uses of xrays

A

look inside bodies
airport security scanners

33
Q

what are 2 uses of gamma rays

A

sterilise food
to detect and treat cancer

34
Q

what is the danger of Xrays and gamma-rays

A

can cause mutations in DNA which can kill cells or cause cancers