The power output for a certain laswer transition was found to be 2.79 watt per square meter. Givne `lambda = 520`nm, calculate the number of quanta emitted per square meter per second.

Explanation

Energy corresponding to the photon `= ( 6.626 xx 10^(-34) xx 3 xx 10^(8))/( 520 xx 10^(-9))`
`= 3.822 xx 10^(-19) J `
the power output `= 2.79 ` Watt `//m^(2)`
`= 2.79 J // `sec `//m^(2)`
`:.` no. of photons emitted per sq. meter sec`= ( 2.79 )/( 3.822 xx 10^(-18)) = 7.20 xx 10^(18)`