A laser beam can be focussed on an area equal to the square of its wavelength. A `He-Ne` laser radiates energy at the rate of `1mW` and its wavelength is `600 nm`. The intensity of focussed beam will be

Options

A. `3.2 xx 10^(9)` W /`m^(2)`
B. `2.8 xx 10^(13)` W /`m^(2)`
C. `2.7 xx 10^(9)` W/`m^(2)`
D. `3.2 xx 10^(13)` W /`m^(2)`

Answer

C

Explanation

`I = (P)/(A) = (P)/(lambda^(2))`