Calculate the number of photons emitted in 10 hours a 60 W sodium lamp (`lambda` of photon =5893 Å)

Options

A. `6.4xx10^(24)`
B. `7.2 xx 10^(24)`
C. `2.1 xx 10^(14)`
D. `3.3 xx 10^(19)`

Answer

A

Explanation

Energy emitted by sodium lamp in one sec.
= Watt `xx` sec `=60xx1J`
Energy of photon emitted `=(hc)/(lambda)`
`=(6.626xx10^(-34)xx3xx10^(8))/(5893xx10^(-10))=3.37xx10^(-19)J`
`:.` No of photons emitted per sec. `=(60)/(3.37xx10^(-19))`
`:.` No. of photons emitted in 10 hours `=17.8xx10^(19)xx10xx60xx60=6.41xx10^(24)`