The number of photons emitted per second by a 60 watt source of monochromatic light of wavelength 663 nm is `(h=6.63xx10^(-34)Js)`

Options

A. `4xx10^(-20)`
B. `1.5xx10^(20)`
C. `3xx10^(-20)`
D. `2xx10^(20)`

Answer

D

Explanation

Energy of one photon `E=hv=(hc)/(lamda)`
`=(6.63xx10^(-34)xx3.0xx10^(8))/(663xx10^(-9))`
NO. of Photons `=60/((6.63xx10^(-34)xx3.0xx10^(8))/(663xx10^(-9)))`
`=(60xx663xx10^(-9))/(6.63xx10^(-34)xx3.0xx10^(8))=2xx10^(20)`