Question

A 100 W incandescent lightbulb emits about 5 W of visible light. (The other 95 W are emitted as infrared radiation or lost as heat to the surroundings.) The average wavelength of the visible light is about 600 nm, so make the simplifying assumption that all the light has this wavelength. How many visible-light photons does the bulb emit per second?

Answer 1

Answer:

n = 1.89 x 10¹⁹ photons/s

Explanation:

given,

Power of bulb = 100 W

Visible light = 5 W

wavelength of the visible light = 600 nm

number of photons emitted per second

using formula of wavelength

$\lambda = \dfrac{c}{\nu}$

$\nu= \dfrac{c}{\lambda}$

$\nu= \dfrac{3 \times 10^8}{600 \times 10^{-9}}$

$\nu=5 \times 10^{14}\ Hz$

energy of photon

U = h υ

U = 6.63 x 10⁻³⁴ x 4 x 10¹⁴

U = 2.65 x 10⁻¹⁹ J

number of photon

$n = \dfrac{P}{U}$

$n = \dfrac{5}{2.65 \times 10^{-19}}$

n = 1.89 x 10¹⁹ photons/s