Calculate the number of photons emitted per second by a 10 watt sodium vapor lamp. Assume that 90% of the consumed energy is converted into light. Wavelength of sodium light is 590nm. `h=6.62xx10^(-34)Js`

Options

A. `1.67xx10^(18)`
B. `1.67xx10^(20)`
C. `2.67xx10^(19)`
D. `3.67xx10^(23)`

Answer

C

Explanation

Energy of photon
`E=(hc)/(lamda)=(6.63xx10^(-34)xx3xx10^(8))/(590xx10^(-9))=(6.63xx3)/59xx10^(-18)`
Light energy produced per second
`=90/100xx10=9w`
`:.` Number of photons emitted per sec
`=(9xx59)/(6.63xx3xx10^(-18))=2.67xx10^(19)`