Properties of waves and EM spectrum

Question 1

Order of waves from long to short wavelength(low to high frequency)
-Sing the song

Answer 1

Radio waves, Microwaves, Infrared (radiation), Visible Light, Ultraviolet, X-rays, Gamma rays

Question 2

What is the EM spectrum

Answer 2

A continuous range of wavelengths/frequencies of electromagnetic waves/radiation (with different uses)

Question 3

How fast do all these waves travel

Answer 3

300,000,000 m/s

Question 4

Uses and dangers of Radio waves

Answer 4

1 Broadcasting on radio or TV
2 communication and satellite transmission
3 Radar
- heats up body tissue

Question 5

Uses and dangers of Microwaves

Answer 5

1 Microwave ovens (heating foods)
2 Satellite communication
-heats up body tissue (specifically water)
-burns

Question 6

Uses and dangers of Infrared

Answer 6

1 heating
2 thermal imaging
3 remote controls
-heating
-skin absorption

Question 7

Uses and dangers of Visible Light

Answer 7

1. seeing and taking photos
2. Fibre optic communications
   -eye damage

Question 8

Uses and dangers of Ultraviolet

Answer 8

1 fluorescent lights
2 sterilisation
3 verifying money, ID, passports
-skin damage (sunburns)
-eye damage (cataracts)
skin cancer (wear sun cream)

Question 9

Uses and dangers of X-rays

Answer 9

1 medical imaging
2 security screening
-damage cells
-ionising radiation can cause cancer risk
-acute radiation sickness

can be blocked by lead screen

Question 10

Uses and dangers of Gamma rays

Answer 10

1 medical imaging
2 cancer treatment
-damage cells
-ionising radiation can cause cancer risk
-acute radiation sickness

can be blocked by lead screen or sometimes concrete

Question 11

Similarities of all EM waves

Answer 11

All travel at speed of light
All transverse waves

Question 12

All waves can be:

Answer 12

Reflected and refracted

Question 13

Law of reflection

Answer 13

Angle of incidence (i) = Angle of reflection (r)

Question 14

Less dense to more dense

Answer 14

Light bends towards normal

Question 15

More dense to less dense

Answer 15

Light bends away from normal

Question 16

Passing along the normal

Answer 16

Light does not bend at all

Question 17

Snell’s Law

Answer 17

n (refractive index) = sini/sinr

Question 18

Doppler Effect definition

Answer 18

The apparent change in wavelength and frequency of a wave emitted by a moving source

Question 19

Explain the Doppler Effect

Answer 19

-Usually when a stationary object emits waves, the waves spread out symmetrically
-When the object moves, the waves get squashed together at one end, and stretched at the other end
-To an observer at the front of the object, the wavelength appears to be smaller and vice versa
= The wavelength decreases at the front (and vice versa)

Question 20

How do ray guns measure the speed of a car

Answer 20

The ray gun emits a wave that reflects off the car
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