In the hydrogen spectrum,the different lines of the Lyman series are present in the:

Find the mass of a photon emitted by a sodium lamp (wavelength $\lambda = 5890 \ \mathring{A}$). How many times is this mass compared to the mass of an electron?

What is light?

Wavelengths of different radiations are given below:
$\lambda(A) = 300 \ nm$
$\lambda(B) = 300 \ \mu m$
$\lambda(C) = 3 \ nm$
$\lambda(D) = 30 \ \mathring{A}$
Arrange these radiations in the increasing order of their energies.

Explain the properties of electromagnetic waves.

The electron is