A pulse of light of duration `100ns` is absorbed completely by a small object initially at rest power of the pulse is `30 mW` and the speed of light is `3 xx 10^(8) ms^(-1)` The final momentum of the object is

Options

A. `0.3 xx 10^(-17) kg ms^(-1)`
B. `1.0 xx 10^(-17) kg ms^(-1)`
C. `3.0 xx 10^(-17) kg ms^(-1)`
D. `9.0 xx 10^(-17) kg ms^(-1)`

Answer

B

Explanation

Change in momentum
`= ("power" xx "total time")/("speed of time") = (P xx t)/(c)`
`1.0 xx 10_(-17) kg xx m//s`