Light with an energy flux of 9` W cm^(-2)` ? falls on a nonreflecting surface at normal incidence. If the surface has an area of `20 cm^(2)`. The total momentum delivered for complete absorption in one hour is

Options

A. `2.16xx10^(-4)kg ms^(-1)`
B. `1.16xx10^(-3)kg ms^(-1)`
C. `2.16xx 10^(-3)kg ms^(-1)`
D. `3.16xx10^(-4)kg ms^(-1)`

Answer

(c)

Explanation

Given, ` I=9 W cm^(-2), A=20cm^(2),` time, `t=60xx60 ` seconds
`I=(Q)/(At)`
`Q=9xx20xx3600`
Total monentum,
`P=(Q)/(C)=(9xx20xx3600)/(3xx10^(8))=2.16xx10^(-3)kgms^(-1)`.