A 600 W mercury lamp emits monochromatic radiation of wavelength 331.3 nm. How many photons are emitted from the lamp per second?
`(h =6.626 xx10^(-34)" Js, velocity of light "=3xx10^(8)ms^(-1))`

Options

A. `1.0 xx10^(19)`
B. `1.0 xx10^(23)`
C. `1.0 xx 10^(21)`
D. `2.0xx 10^(23)`

Answer

C

Explanation

Energy emitted by the bulb = 600 W `= 600 Js^(-1)` `(1W = 1 Js^(-1))`
`lambda = 331.3 xx 10^(-9) m`
Energy of one photon `= hv = (hc)/(lambda) = (6.62 xx10^(-34) xx 3 xx 10^(8))/(331.3 xx 10^(-9))`
` = 0.059 xx 10^(-7)~~ 0.06 xx 106(-17)J`
No. of photon emitted from the lamp per second ` = (600)/(0.06 xx 10^(-17)) = 1.0xx10^(21)`