The wavelength of a photon is $5000 \mathring A$. Its energy will be:

The value of Planck's constant is

Write the equation for the energy of a photon.

What is a photon?

$A$ particle which has zero rest mass and non-zero energy and momentum must travel with a speed

There are $n_1$ photons of frequency $\nu_1$ in a beam of light. In an equally energetic beam,there are $n_2$ photons of frequency $\nu_2$. Then the correct relation is