Radiation force on a solid hemisphere

  • #1
Krushnaraj Pandya
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Homework Statement


A perfectly reflecting solid hemisphere of radius R is placed in the path of a parallel beam of light of large aperture, if the beam carries an intensity I, what is the force exerted by the beam on the hemisphere?

Homework Equations


radiation pressure=I(1+ro)(cos^2(x))/c
I is intensity, po is reflection coefficient, x is angle of incidence and c is speed of light.

The Attempt at a Solution


ro=1 here, Intuitively the force will be less than on a disc of the same radius, so it is less than 2*pi*r*r*I/c, I also know integration will be involved but I can't figure out how to go about it. I'd appreciate some help, thank you
 

Answers and Replies

  • #2
haruspex
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integration will be involved
For any particular photon, what component of the impulse it applies is relevant?
Consider an element of the hemisphere over which that component is approximately constant.
 

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