Question

What is the energy of a photon of blue light with a wavelength of 460 nm?

Answer 1

Answer: $E=4.321(10)^{-19} J$

Explanation:

The energy $E$ of a photon is given by:

$E=h\nu$ (1)

Where:

$h=6.626(10)^{-34}\frac{m^{2}kg}{s}$ is the Planck constant

$\nu$ is the frequency light

On the other hand, there is an inverse relationship between $\nu$  and the wavelength $\lambda$:

$\nu=\frac{c}{\lambda}$ (2)

Where:

$c=3(10)^{8} m/s$ is the speed of light

$\lambda=460 nm=460(10)^{-9}m$ is the wavelength

Substituting (2) in (1):

$E=\frac{hc}{\lambda}$ (3)

$E=\frac{(6.626(10)^{-34}\frac{m^{2}kg}{s})(3(10)^{8} m/s)}{460(10)^{-9}m}$

Finally:

$E=4.321(10)^{-19} J$ This is the energy of a photon of blue light, in Joules.