Question 205: EM waves

Question

Light with an energy flux of 25 $$ 	imes $$ 104 W m$$-$$2 falls on a perfectly reflecting surface at normal incidence. If the surface area is 15 cm2, the average force exerted on the surface is

Accepted Answer

For a perfectly reflecting surface, the average force exerted on the surface is
F = $${{2IA} \over c}$$
= $${{2 	imes 25 	imes {{10}^4} 	imes 15 	imes {{10}^{ - 4}}} \over {3 	imes {{10}^8}}}$$
= 2.50 $$ 	imes $$ 10
$$-$$6
N

Answer

1.25 $$ 	imes $$ 10$$-$$6 N

Answer

2.50 $$ 	imes $$ 10$$-$$6 N

Answer

1.20 $$ 	imes $$ 10$$-$$6 N

Answer

3.0 $$ 	imes $$ 10$$-$$6 N

EM waves

Light with an energy flux of 25 $ \times 104 W m-$2 falls on a perfectly reflecting surface at normal incidence. If the surface area is 15 cm2, the average force exerted on the surface is

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