Waves (EM spectrum)

what is a transverse wave?

a transverse wave is a wave for which the direction of vibration is perpendicular to the direction of travel

e.g. light waves

what is a longitudinal wave?

a longitudinal wave is a wave for which the direction of vibration is parallel to the direction of travel

e.g. sound waves

definition of wavelength

distance between a point on a wave and the same point on the next wave

definition of amplitude

height of the wave from the resting position (written as A)

definition of wavefront

a line joining up points that are all at the same point of a wave cycle

definition of time period

the time taken for one complete wave to pass a point

definition of frequency

how many complete waves pass a point every second (measured in Hertz - Hz)

what do waves transfer?

waves can transfer energy and information without transferring matter

what is the equation linking frequency, wavelength and velocity?

wave speed = frequency x wavelength

v = fλ

what is the equation linking frequency and time period?

frequency = 1/time period

time period = 1/frequency

what can happen to waves when they hit a surface?

they can be reflected

what happens to waves when they pass through a boundary between two media?

they are refracted

what are the types of waves on the EM spectrum?

radio waves, microwaves, infra-red, visible light, ultra-violet, x-rays, gamma rays

what is the type of wave with the longest wavelength and lowest frequency?

radio waves

what is the type of wave with the shortest wavelength and highest frequency?

gamma rays

what are the uses and dangers of radio waves?

uses - communication and radio/tv

dangers - none

what are the uses and dangers of microwaves?

uses - satellite comms and cooking

dangers - internal burns

what are the uses and dangers of infra-red waves?

uses - heaters and night vision goggles

dangers - skin burns

what are the uses and dangers of visible light waves?

uses - photographs and eyesight and optical fibres

dangers - none

what are the uses and dangers of ultra-violet waves?

uses - fluorescence and sterilisation

dangers - sun burn → skin cancer

what are the uses and dangers of x-rays?

uses - internal scanning

dangers - DNA mutation → cancer

what are the uses and dangers of gamma rays?

uses - sterilising and radiotherapy

dangers - DNA mutation → cancer

what type of waves are electromagnetic waves (EM waves)?

waves in the electromagnetic field

can electromagnetic waves travel through a vacuum?

yes they can

what speed do the electromagnetic waves go at in a vacuum?

they travel at the speed of light

what type of wave are electromagnetic waves?

transverse waves

what do electromagnetic waves transfer?

they transfer energy