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An isotropic point source of radiation power P is located on the axis of an ideal mirror plate. The distance between the source and the plate exceeds the radius of the plate eta-fold. In terms of the corpuscular theory find the force that light exterts on the plate. |
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Answer» <P> SOLUTION :CONSIDER a ring of radius `x` on the plate. The normal PRESSURE on this ring is, by problem`(2)/(c )(P)/(4PI(x^(2)+eta^(2)R^(2))).cos^(2)theta` `=(P)/(2pic) (eta^(2)R^(2))/((x^(2)+eta^(2)R^(2))^(2))` The total force is then `underset(0)overset(R)int (P)/(2pic)(eta^(2)R^(2))/((x^(2)+eta^(2)R^(2))^(2))2pixdx` `=(Peta^(2)R^(2))/(2c) underset(eta^(2)R^(2))overset(R^(2)(1+eta^(2)))int (dy)/(y^(2))` `= (Peta^(2)R^(2))/(2c) [(1)/(eta^(2)R^(2))-(1)/(R^(2)(1+eta^(2)))] = (P)/(2c(1+eta^(2)))` 
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