A 100 watt bulb emits monochromatic light of wavelength 400 nm. Calculate the number of photons emitted per second by the bulb.

Options

A. `2xx10^(20)`
B. `2xx10^(18)`
C. `2xx10^(16)`
D. `2xx10^(22)`

Answer

A

Explanation

A 100 watt buib emits ……..
Power of the bulb = 100 watt
`100 Js^(-1)`
Energy of one photon `E = hv = hc//lambda`
`= 6.62xx10^(-34)Jsxx3xx10^(8)ms^(-1)//400xx10^(-8)m`
`= 4.96xx10^(-19)J`
Number of photons emitted
`= 100 Js^(-1)//4.96xx10^(-19)J`
`= 2.01xx10^(20)s^(-1)`