Question

Light with an energy flux of 25×104Wm−2 falls on a perfectly reflecting surface at normal incidence. If the surface area is 15 cm2, the average force exerted on the surface is1.25×10−6N2.50×10−6N1.20×10−6N3.0×10−6N

Solution

The correct option is B 2.50×10−6NFav=2IAc=2×25×104×15×10−43×108=250×10−8N=2.5×10−6N

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