Question

Find out the no of photons emitted by a 60 watt bulb in one minute if wavelength of an emitted photon is 62 nm

Answer 1

E=power×time(in sec) E=60×60=3600J follow the remaining answer in the image below

Answer 2

Concept:

A photon is the smallest distinct quantity of electromagnetic energy or quantum. It is the fundamental unit of all light.

Photons are continually in motion and, in a vacuum, move at a constant speed of 3 x 10⁸ m/s to all observers. This is usually known as the speed of light, which is symbolized by the letter c.

Given:

The wavelength of an emitted photon = 62 nm = 62 * 10⁻⁹ m

Power = 60 W

Find:

Find out the number of photons emitted by a 60 watt bulb in one minute if the wavelength of an emitted photon is 62 nm.

Solution:

The electrical energy supplied in one minute = 60 J (because power = 60 W)

The electrical energy supplied in one second = $\frac{60 }{60}$ J/s = 1 J/s

The energy of each photon can be calculated as:

E = $\frac{hc}{lamda}$

where h is the Planck's constant = 6.626 * 10⁻³⁴ J s

c is the speed of light = 3 * 10⁸ m/s

lambda is the wavelength of an emitted photon.

By substituting these values in the above expression, we can calculate the energy of each photon.

E = $\frac{6.626 * 10^{-34} * 3 * 10^{8} }{62 * 10^{-9} }$

​E = 0.3206 * 10⁻¹⁷ J

Now, the number of photons can be calculated as:

The number of photons = $\frac{energy per second}{energy of photon}$ = $\frac{1}{0.3206 * 10^{-17} }$ = 3.119 * 10¹⁷

Hence, the number of photons emitted by a 60 watt bulb in one minute if wavelength of an emitted photon is 62 nm is 3.119 * 10¹⁷.

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