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

Answer

`2.67xx10^(19)`

Explanation

Power of light emitted by lamp,
`P=90/100xx10=9`watt
Energy of photon=`(hc)/lambda`
`=(6.63xx10^(-34)xx3xx10^(8))/(590xx10^(-9))J`
No. of photons emitted per second `=P/(hc//lambda)`
`=(9xx590xx10^(-9))/(6.63xx10^(-34)xx3xx10^(8))=2.67xx10^(19)`