NEET Questions Solved

NEET - 2015

A radiation of energy 'E' falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (c=velocity of light)

(a)E/c

(b)2E/c

(c)2E/c2

(d)E/c2

The radiation energy is given by

E=hc/λ

Initial momentum of the radiation is

Pi=h/λ=E/c

The reflected momentum is

Pr=-h/λ=-E/c

So, the change in momentum of light is
ΔPlight=Pr-Pi=-2E/c

Thus, the momentum transferred to the surface is
ΔPlight=2E/c

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