Light with an average flux of `20 W/cm^2` falls on a non-reflecting surface at normal incidence having surface area `20 cm^2`. The energy received by the surface during time span of 1 minute is:

Options

A. `12 xx 10^3J`
B. `24 xx 10^3 J`
C. `48 xx 10^3 J`
D. `10 xx 10^3 J`

Answer

B

Explanation

Intensity `(I) = E/(At)`
`therefore ` Energy `(E) = Iat = (20)/(10^(-9)) xx 20 xx 10^(-9) xx 60`
`= 24 xx 10^3 J`