Question
Thu March 29, 2012 By: Advait Vasavada
1) the light is absorbed totally
2) the light is reflected totally
3) the fraction of light reflected is

Derive formula for force on a plate of mass m if a light of intensity I is illuminated on it within area A, wavelength is lamda . derive formula of force for 4 following cases

Expert Reply
Wed May 08, 2013
1.when the light is absorbed totally,the momentum of light is totally transfered in elestic collision.
initial momentum associated with light=p=U/c
So change in momentum/time hence force=-U/c
2) When the light is reflected totally,
change in momentum/time=-p-p=-2p=-2U/c, hence force.
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