Wavenumber for a radiation having $5800 \ \mathring{A}$ wavelength is $x \times 10 \ cm^{-1}$. The value of $x$ is . . . . . . . .

An atom emits energy equal to $4 \times 10^{-12} \, erg$. To which part of the electromagnetic spectrum does it belong?

Yellow light emitted from a sodium lamp has a wavelength $(\lambda)$ of $580 \,nm$. Calculate the frequency $(v)$ and wave number $(\bar{v})$ of the yellow light.

Give the characteristics of electromagnetic radiation. Give the relation between them.

The hydrogen spectrum from an incandescent source of hydrogen is:

Which formula represents the rest mass of an electron?