Wave Motion (16) Flashcards
Mechanical Waves
- require a medium to travel through
- disrupt the medium physically
Electromagnetic Waves
- Do not require a medium to travel through
- cause electric and magnetic disruption
travelling waves
- carry energy away from its source through a medium without any overall movement of the medium
longitudinal waves
- the direction of vibration is parallel to the direction in which the wave is travelling
transversal waves
- the direction of vibration is perpendicular to the direction in which the wave is travelling
- all EM waves
Wavelength
- length of a complete cycle
- antinode to antinode (crest to crest) or node to node (transversal)
- compression to compression/rarefaction to rarefaction (longitudinal)
- λ
- metres
Amplitude
- the maximum displacement from the mean position
- the distance between the base line and the crest/trough
Frequency
- number of vibrations per second
- f
- Hz
Speed
- speed at which the wave propagates through the medium
- c
- m/s
Period
- time taken for the cycle to occur
- T
- seconds
- T = 1/f
wave formula
c = f λ
reflection
the bouncing of a wave off an object
Refraction
the bending of a wave as passes from one medium to another and changes speed
Diffraction
the spreading out of a wave as it moves through a gap or around an obstacle
interference
when waves combine to form a resultant amplitude which is made up of each waves individual amplitude
constructive interference
when waves combine to form a resultant amplitude greater than each individual waves amplitude
destructive interference
when waves combine to form a resultant amplitude smaller than each individual waves interference
coherant waves
two waves that are in step or a fixed amount out of step which produce an interference pattern
in phase
causes constructive interference
180° out of phase
causes destructive interference
polarisation
a wave is confined to a particular plane
stationary waves
waves of the same frequency and amplitude that constructively and destructively interfere to produce a wave pattern in a confined space
doppler effect
- the apparent change in frequency due to the relative motion of source and observer
- higher apparent frequency when moving towards a person
- lower apparent frequency when moving away
node
the minimum displacement of a wave from its base level
antinode
the maximum displacement of a wave from its base level
Red and Blue shift
- low frequency is red (moving away)
- high frequency is blue (moving towards)
- used to measure the velocity of stars
