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  • Created by: Jaz Higgs
  • Created on: 04-06-14 14:34

Nature of Light Formulae

E= hf = hc/lambda 

h= plack's constant (6.63x10^-34) 

f- frequency (hz) 

lambda- wavelength (m) 

c- speed of light in a vacuum (3.00x10^8ms-1) 

eV= 1/2 mv2 

eV- electron volt 

m- mass 

v- velocity 

1eV- 1.6x10^-19J 

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Nature of Light Formulae 2

f= work function/h 

f- frequency 

h- planck's constant (6.63x10^-34) 

hf=1/2mv max2 + work function 

Radiation flux= power/area  

wm-2=w/m2 


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Waves- ENERGY

A progressive wave carries energy from one place to another without transferring any material. 

For example: 

1) electron-magnetic waves cause things to heat up 

2) gamma rays knock electrons out of their orbit, causing ionisation 

3) wave power can be used to generate electricity

PARTS OF THE WAVE 

displacement- how far a point on the wave has moved from its undisturbed position 

amplitude- maximum displacement 

wavelength- the length of one whole wave, from crest to crest or trough to trough 

period- the time taken for a whole vibration 

frequency- the number of vibrations per second passing a certain point 

phase difference- the amount by which one wave lags behind another 

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Reflection, refraction and frequency

reflection- the wave is bounced back when it hits a boundary 

refraction- the wave changes direction as it enters a different medium 

frequency= 1/period 

the frequency is the inverse of the period. Get the units straight: 1hz= 1s^-1 

s=d/t 

speed of wave =lambda (wavelength) x frequency 

v= d/t -> v=lambda/ 1/f 

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