Question

A light of frequency 5×10^14Hz is emitted from a 20 walt bulb.Find out the number of photons emitted per second from bulb.

Answer 1

Here is the answer to the question

Answer 2

HELLO THERE!

Given: Power of the bulb = 20 W

This means that, the bulb spends 20 Joule energy in 1 second.

Frequency (f) = 5 x 10¹⁴ Hz

Let n be the number of photons emitted per second.

Since number of photons emitted in one second is asked, we need the energy spent by the bulb in one second, which is 20 J.

Plank's constant h = 6.626 x 10⁻³⁴ Js

We know,

$E = nhf \\\\\implies n = \frac{E}{hf} \\\\\implies n = \frac{20}{6.626\times10^{-34}\times5\times10^{14}} \\\\\implies n = 6.03\times10^{19}$

So, this was your answer.

Hope it helps :)