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Flashcards in 1) Waves Deck (50)
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1
Q

Define transverse waves

A

Particles vibrate perpendicularly to the direction of energy transfer

2
Q

Define longitudinal waves

A

Particles vibrate parallel to the direction of energy transfer

3
Q

What is the wavelength?

A

distance between two peaks

4
Q

What is the amplitude?

A

distance from peak to the middle

5
Q

What is the symbol for wavelength?

A

Greek letter pronounced lambda [ λ ]

6
Q

What is frequency measured in?

A

Hertz (Hz)

7
Q

What does a frequency of 1 Hz mean?

A

1 wave per second

8
Q

What is the time period of a wave?

A

The time taken to produce one wave

9
Q

What is the equation linking time period (T) and frequency (f)?

A

T = 1/f

10
Q

What is the equation relating wave speed (v), frequency (Hz) and wavelength (lambda)?

A

“wave speed = frequency bywavelength”

11
Q

What is wavespeed measured in?

A

m/s

12
Q

What is wavelength measured in?

A

metres

13
Q

What are the uses of radio waves?

A
  • broadcasting

- communications

14
Q

What are the uses of microwaves?

A
  • cooking

- satellite transmissions

15
Q

What are the uses of infrared?

A
  • heaters

- night vision equipment

16
Q

What are the uses of visible light?

A
  • optical fibres

- photography

17
Q

What are the uses of ultraviolet?

A
  • fluorescent lamps
18
Q

What are the uses of x-rays?

A
  • observing the internal structures of objects and materials, including for medical applications
19
Q

What are the uses of gamma rays?

A
  • sterilising food

- medical equipment

20
Q

What type of waves has the longest wavelength and lowest frequency?

A

Radio waves

21
Q

What type of waves have the shortest wavelength and highest frequency?

A

Gamma rays

22
Q

List the 7 types of radiation in the electromagnetic spectrum in order of lowest frequecy and longest wavelength to highest frequency and shortest wavelength

A
  • radio waves
  • microwaves
  • infra-red
  • visible light
  • ultra violet
  • X-rays
  • gamme rays
23
Q

What effects on the body do microwaves have?

A
  • internal heating of body tissue
24
Q

What effects on the body does infrared have?

A
  • skin burns
25
Q

What effects on the body do radiowaves have?

A
  • none
26
Q

What effects on the body does visible light have?

A
  • blindness
27
Q

What effects on the body does ultra violet have?

A
  • damage to surface cells
  • cancer
  • blindness
28
Q

What effects on the body do gamma rays have?

A
  • cancer

- DNA mutations

29
Q

Define Doppler effect

A

“The change in wave frequency during the relative motion between a wave source and its observer”

30
Q

How long are the wavelengths when the sound is travelling towards the observer?

A
  • short
  • high frequency
  • high pitched sound
31
Q

How long are the wavelengths when the sound is travelling away from the observer?

A
  • longer wavelength
  • lower frequency
  • lower pitch
32
Q

Define incident ray

A

The ray of light that is going towards the normal

33
Q

Define reflection ray

A

The ray that is going away from the normal

34
Q

What is the law of reflection?

A
  • That i=r

- angle of incidence = angle of reflection

35
Q

What degree is the normal to the mirror/glass block?

A

90° or perpendicular

36
Q

Define critical angle

A

The angle where light will be refracted along the surface of the material

37
Q

What is the critical angle of glass?

A

42°

38
Q

Define total internal reflection

A

When the angle of incidence is greater that the critical angle, all the light is reflected

39
Q

What happens in an optical fibre?

A

The light travels down the fibre by repeated total internal reflection

40
Q

Define refraction

A

Refraction is the change in direction of light as it enters either a more or less dense medium and either slows down or accelerates.

41
Q

What is the name given to a medium which light travels slower?

A

Optically dense

42
Q

What happens when light enters a more optically dense material?

A

The light refracts towards the normal

43
Q

What happens when light enters a less optically dense material?

A

The light refracts away from the normal

44
Q

Define refractive index (n)

A

The ratio of the speed of light in a material to the speed of light in a differently dense material

45
Q

How do you find the refractive index?

A

n = sin i (angle of incidence)/ sin r (angle of refraction)

46
Q

Rearrange the refractive index equation to find i (angle of incidence)

A

i = sin-1(n sin r)

47
Q

Rearrange the refractive index equation to find r (angle of refraction)

A

r = sin-1(sin i/n)

48
Q

What is the equation linking critical angle (c) and the refractive index (n)?

A

sin c = 1/n

49
Q

Can sound travel through a vacuum?

A

no

50
Q

Are sound waves transverse or longitudinal waves?

A

Longitudinal