Karteikarten
Physics Revision
Karten in diesem Stapel (11)
- 1LONGITUDINAL WAVES -sound waves -ultrasound waves (higher frequency than the human ear can hear) -P waves (earthquake pressure waves) -they need particles to be transmitted through for example air. -they are pressure waves and oscillate in the same direction the wave is travelling.TRANSVERSE WAVE
-do not need particles to travel through
-can travel through a vacuum
-energy wave
-the ossolation of the wave is across/90 degrees/perpendicular to the direction of the wave
-S waves
-the electromagnetic spectrum; light, radio, infra-red, gamma, x-rays, microwaves and UV - 2PERIODIC TIME- measured in seconds (s) and is the time taken for 1 full waveFREQUENCY- measured in hertz (Hz) and is the number of waves that ass a certain point per second.
- 3SPEED = DISTANCE/TIMEWAVE EQUATION-
V=f/lamda
OR
wave speed (ms-1)=frequency(Hz) x wavelength (m) - 4UNPOLARISED LIGHT- a normal light bulb, the sun and most light sources produce this. it is a transverse wave and its displacement is at right angles (90 degrees) to the direction of travel. however it can oscillate in any direction.PLANE POLARISED LIGHT- when passed through a polarising filter (crystalline material) the light waves oscillate in one direction only and are absorbed in all others. radio waves and microwaves are produced as plane polarised waves.
- 5REFLECTED LIGHT- this is partially polarised with mainly the horizontal plane transmitted, wearing polaroid sunglasses/ using camera filters can reduce this 'glare' REFRACTION- frequency's conserved (constant) as a wave moves across a boundary into a new material.STRAIN ANALYSIS- some plastics can rotate the plane of polarisation, so if placed between 2 crossed filters.
MICROWAVES- these are produced by the transmitter already plane polarised. - 6RADIO AND TV- these signals are sent out from the main transmitter already polarised horizontally. booster transmitters around the country send out vertically polarised waves, which do not interfere with the main signal.REFRACTION- the change of direction of a ray of light, sound, heat in passing obliquely from one medium to another
the frequency is fixed but if the wavelength decreases so does the wave speed or if you increase the wavelength the wave speed also increases. - 7PREFIXES- pm= pico= 0.00000000001 cm= centi= 0.01 dm= deci= 0.1 mm= milli= 0.001 ym= micro= 0.000001 nm= nano= 0.000000001STEP INDEX- a refractive index profile characterized by a uniform refractive index within the core and a sharp decrease in refractive index, core is pure and consistent.
- 8GRADED INDEX- an optical fibre whose core has a refractive index that decreases with increasing radial distance from the optical axis of the fibre.MONO MODE- denoting or relating to a type of optical fibre with a core less than 10 micrometres in diameter, only rays parallel t the core are transmitted
- 9HOW OPTICAL FIBRES WORK- conditions: the light must be shone in from within the acceptable zone (greater than the critical angle) and the cladding must have a lower value of n than the core.CORE= pure silicon dioxide (glass)
CLADDING= glass with added boron, refractive index only 1% smaller than the core for it to work. - 10PHASE DIFFERENCE: the phase refers to the point you are at on a wave, and can be compared to another point. it may be referred to as a proportion of the full wave length (Y), or as an angle (degrees C or in radians) or as a time difference.360 degrees = 2 pi radians
- 11STANDING WAVES= standing waves are set up as a result of two waves with the same amplitude and frequency travelling at the same speed, but in different directions. (the difference between two nodes or between two anti-nodes is half a wavelength.the reflective wave and the incoming wave interfere, for example, at the reflecting surface the two waves are always exactly opposite, this is called a node, at other points along the waves the two waves are the same, this is an anti node.
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- Karteikarten am Physics Revision , erstellt von 09little.m am 22/02/2016.
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