physics p1
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- Created by: lauren winchester
- Created on: 11-10-12 20:43
ENERGY TRANSFER
- Energy can be transfered or dispersed but cannot be destroyed
- Only part of the energy is useful, the rest is wasted
- The wasted enrgy spreads out and becomes less useful
efficiency - useful energy/total energy in (x100)
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TRANSFERING ELECTRICAL ENERGY
- the amount of energy transfered depends on the power and time it is on
- E=pxt
- E= energy in kilo-watt hours (kWh)
- p= power in kilo-watts (kW)
- t= time in hours(h)
OR
- E=energy transfered in joules (J)
- p=power in watts (W)
- t= time in seconds(s)
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WAVES
- transverse or longitudinal
- electromagnetic waves are transvers
- soundwaves are longitudinal
- mechanical waves can be either transverse or longitudinal
- longitudinal waves show areas of refraction and compression
- waves can be reflected, refracted and diffracted
- waves change direction when they are refracted
- v=fxw
- v= speed in metres per second (m/s)
- f= frequency in hertz (hz)
- w= wavelength in metres (m)
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REFLECTION
- the normal is a construction line perpendicular to the reflecting surface
- the angle of incidence is equal to the angle or reflection
- the image produced in a plane mirror is virtual, upright and laterally inverted
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SOUND
- sound waves are longitudinal
- sound waves cause vibrations detected as sound
- pitch is determined by frequency
- loudness is determined by amplitude
- echos are reflections of sounds
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INFRA-RED RADIATION
- all objects emit and absorb infra-red
- the hotter an object the more infra-red emitted
- dark, matt surfacers are good absorbers and emitters
- light, shiny surfaces are poor absorbers and emmiters
- light, shiny surfaces are good reflectors of infra-red
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HEATING AND INSULATING BUILDINGS
- U-values measure how effective an insulator is
- the lower the u-value the better the material
- solar panels contain water heated by the sun; used to heat buildings and as hot water
- specific heat capacity is energy needed to raise temp by one degree of a one kilo sample
- E=mxcxt
- E = energy transfered (J)
- m = mass (kg)
- t = temperature change (degrees)
- c = specific heat capacity (J/kg C)
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ELECTRO-MAGNETIC WAVES
- all types travel at the same speed through a vaccum
- Form a continuous spectrum
Radio waves, microwaves, infra-red radiation, visible light, ultra violet, x-rays, gamma rays
- radio waves, microwaves, infra-red and light can be used as forms of communication
- radio waves - t.v. and radio
- microwaves - mobiles and satellite t.v.
- infra-red - remotes
- visible light - photos
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RED SHIFT
- the doopler effect is the change in wave length and frequency observed when a wave source is moving relative to an observer
- wave source could be light or sound or microwaves
- as it moves away wavelenght increases and frequency decreases
- as it move towards wavelength decreases as frequency increases
- the further a way a galaxy is, the faster it is moving, the more red-shift is detected
- Red shift supports the 'Big bang theory'
- cosmic microwave background radiation comes from the radiation present shortly after the universe began
- 'Big bang theory' is only theory that supports CMBR
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