AS Waves

61572747	Electromagnetic Wave	Consists of the oscillation of electric & magnetic fields, transverse waves
61572748	Transverse Waves	Direction of oscillation is at 90° to the direction the wave energy is travelling
61572749	Longitudinal Waves	Direction of oscillation is in the same direction the wave energy is travelling
61572751	Time Period	The time taken to complete one complete oscillation
61572753	Frequency	Number of oscillations / time taken
61572754	Time Period =	1 / Frequency
61572755	Wave Length λ	The distance between points at the same phase on neighbouring wave cycles
61572756	V =	fλ
61572757	When waves are incident on a boundary between two different media	Some of the wave energy is reflected and some is transmitted
61572758	Refraction	The change in wave velocity which results when waves travel from one medium to another which usuallly results in a change in direction
61572759	Diffraction	The spreading out of wave energy as waves move through a narrow gap or past a narrow obstacle
61572760	For significant diffraction to occur	The gap must be of similar size to the wavelength
61572761	The Principle of Superposition	The resulting disturbance at each instant is the vector sum of the individual wave disturbances at that point
61572762	Constructive Interference	Occurs when waves that are in phase are superposed
61572763	Destructive Interference	Occurs when waves that are π out of phase are superposed
61572764	Coherent Waves	Waves with a constant phase difference
61572765	Coherent Wave Sources	Produce waves with a constant path difference
61572766	Path Difference	The difference between, the distance from the source to a point, for two waves
61572767	Intensity =	Power / Area
61572768	Intensity α	Amplitude²
61572770	Monochromatic Light	Single wave length light
61572771	Coherent Light	Constant uninterupted flow of light
61572772	Laser light produces	Continous coherent waves
61572773	Diffraction Grating consists of	a large number of evenly spaced slits
61572774	Path Difference:	dsinø = nλ (where d is source seperation)
61572775	As the number of slits increases	the dark fringes expand and the bright fringes are more defined
61572776	Node	Point on a standing wave with minimum amplitude caused by destructive interference
61572777	Anti-Node	Point on a standing wave with maximum amplitude caused by constructive interference
61572778	Standing waves occur when	Progressive waves are reflected by two boundaries so that the wave energy is contained within a fixed region. Two coherent waves travelling in opposite directions are superposed to produce a wave interference pattern
61572780	When light is reflected	it is partially polarised
61572781	Plane of polarisation	the plane in which oscillation occurs
61655843	rest line	the line from which the vibration is measured; matter at rest
61655844	vibration	a repeated back and forth motion that creates a wave
61655845	compression	when the particles are squeezed together
61655846	wave	a travelling disturbance that moves energy, not matter
61655847	crest	the highest point of wave.
61655849	amplitude	the distance from the rest position to the crest or trough
61655850	mechanical wave	a wave that requires a medium through which to travel
61655851	medium	matter (solid, liquid, gas) through which a wave travels
61655852	hertz	the unit of frequency equal to cycle per second; Hz
61655853	seismic wave	A vibration that travels through Earth carrying the energy released during an earthquake
61655854	absorb	to take in
61655855	transmit	to send on, pass along, send out
61655856	trough	lowest point of the wave
61655857	reflect	bouncing of a wave or ray off a surface, changing its direction
61655858	constructive interference	Addition of two waves when the crest of one overlaps the crest of another, so that their individual effects add together. The result is a wave of increased amplitude.
61655859	destructive interference	Addition of two waves when the crest of one overlaps the trough of another, so that their individual effects cancel each other. The result is a wave of decreased amplitude.
61655860	rarefaction	a part in a longitudinal wave where the particles are spread apart