Question

a bulb emits light of wavelength 4500Å.The bulb is rated as 150 watt and 8% of the energy is emitted as light.How many photons are emitted by the bulb per second?

Answer 1

Answer : $2.72\times 10^{19}$ photons are emitted by the bulb per second.

Explanation:

Wavelength of the light = 4500 $\AA$

$1\AA=10^{-10} m$

Energy of one photon = $E=\frac{hc}{\lambda }$

$E=\frac{6.62\times 10^{-34} J/s\times 3\times 10^{8}m/s}{4500\times 10^{-10} m}=4.41\times 10^{-19} J$

$E_n=n\times 4.41\times 10^{-19} J$ = Total energy of n numbers of photons

The bulb is rated as 150 watt and 8% of the energy is emitted as light:

Power = 150 watts ,Time =  1 seconds

$Energy=Power\times time= 150 watts\times 1 s = 150 J$

Total energy of bulb = 150 J.

Energy emitted as light:

$=E_L=150 J\times \frac{8}{100} J$

$E_n=E_L$

$E_n=n\times 4.41\times 10^{-19} J=150 J\times \frac{8}{100} J$

$n=2.72\times 10^{19} photons$

$2.72\times 10^{19}$ photons are emitted by the bulb per second.

Answer 2

Answer:

Explanation:

Please refer the below attachment.