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Wave defintion
Transfer of energy without the transfer of matter by means of oscillation
What can oscillate to form a wave
Matter or fields
What is the difference between longitudinal waves and transverse waves
Transverse waves oscillate perpendicular to energy transfer, and longitudinal oscillate parallel
Example of longitudinal waves
P-waves, sound
Example of transverse waves
S-waves, light, string
What are the parts of longitudinal waves
Rarefaction and compression
How are the two ways waves can be graphed
Displacement against time or distance
Definition of amplitude
Maximum displacement from rest value
Definition of time period
Time for 1 complete oscillation
Definition of frequency
How many waves pass a point in 1 second
What is superposition
When waves overlap, the resulting wave is the sum of the overlapping waves
What is phase difference
The difference 2 points on 2 coherent waves
Coherence definition
Constant phase difference and same frequency
What happens when 2 identical waves travel in opposite directions
A standing wave is formed with 2 * amplitude
What is path difference
The difference in the distances that 2 waves travel between 2 points
In a stationary wave, what is the phase difference
At an odd number of anti nodes away, out of phase, an even number of anti nodes away is in phase
What is polarisation
Restriction of the oscillation of a wave into 1 plane
Why can longitudinal waves not be polarised
Because they can only vibrate in one direction (can’t be restricted to a plane
What direction of polarisation passes through a vertical polaroid
A vertical polarisation (opposite polarisations can’t get through the polaroid)
How much unpolarised light gets through a polaroid
The intensity halves
How do sunglasses use polarisation
They have a vertical polaroid, which halves the intensity of light from the sun, and eliminates the horizontally polarised light from reflections so it is easier to see
How do we consider polarised light with microwaves
An antennas oscillating electric field forms vertically polarised light so receiving antenna must be the same direction, A vertical metal grid between the source and receiver will block (horizontal polaroid)
What is an easy way to set up a standing wave
Reflecting a wave back on itself with a string
What are the frequencies of a standing wave called
Resonant frequencies
How many anti nodes are there on the nth harmonic
n+1
What pattern does a tube with powder and a loudspeaker show
there are piles of powders equally spaced at the antnodes