What is the energy of a photon of light with a wavelength of 575 nm?

1 Answer
Nov 27, 2015

Answer:

3.46⋅10−19J

Explanation:

The energy of a photon is proportional to its frequency, as stated by the Planck - Einstein's equation

E=h⋅ν , where

E - the energy of the photon
h - Planck's constant, equal to 6.626⋅10−34J s
ν - the frequency of the photon

Now, notice that you are given the wavelength of the photon, λ. As you know, frequency and wavelength have an inverse relationship described by the equation

λ⋅ν=c , where

c - the speed of light in vacuum, approximately equal to 3⋅108m s−1

This means that the relationship between energy and wavelength looks like this

λ⋅ν=c⇒ν=cλ

E=h⋅cλ

Another important thing to notice here is that the wavelength of the photon is given in nanometers, nm. You need to convert this to meters, the unit used for the value of the speed of light.

E=6.626⋅10−34Js⋅3⋅108ms−575⋅10−9m=3.46⋅10−19J