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A plate of mass 10g is in equilibrium in...

A plate of mass 10g is in equilibrium in air due to the force exerted by a light beam on the plate. Calculate power of the beam. Assume that the plate is perfectly absorbing.

Text Solution

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For equilibrium the force exerted by the light beam should balance the weight of plate.
`F_(photon)=mg`
`(F_("photons"=(IA)/c=(P)/c "where power" P=IA)`
`implies(P)/(c)=10xx10^(-10)xx10`
`P=3xx10^(7)W`
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