A laser beam is operating at 100 mW. The amount of energy stored by 90 cm length of this laser beam will be

Options

A. `2 xx 10^(-10) J`
B. `3 xx 10^(-10) J`
C. `8 xx 10^(-11) J`
D. `6 xx 10^(-11) J`

Answer

B

Explanation

Energy of LASER beam ,
` = (Il)/( C ) = (100 xx 10^(-3) xx 90 xx 10^(-2) )/(3 xx 10^8) = 3 xx 10^(-10) J`