A 25 watt bulb emits monochromatic yellow light of wavelength of ` 0. 57 mu` m. Calculate the rate of emission of quanta per second .

Options

A. `5.89 xx 10^15 sec^-1`
B. `7.28 xx 10^17 sec^-1`
C. `5 xx 10^(10)- sec^-1`
D. `7.18 xx 10^-19 sec^-1`

Answer

D

Explanation

(d) Let `n` quanta are evolved per sec
`n[(hc)/(lamda)] = 25 J sec^-1`
`n (6.626 xx 10^-34 xx 3 xx 10^8)/(0.57 xx 10^-6) = 25`.
`n= 7.18 xx 10^(-19)sec^(-1)`