$\alpha$-rays have

$A$ gas absorbs a photon of $355 \ nm$ and emits at two wavelengths. If one of the emissions is at $680 \ nm,$ the other is at : ................. $nm$

Calculate the wave number and frequency of orange radiation having wavelength $6300 \ \mathring{A}$.

Splitting of spectral lines when atoms are subjected to a strong electric field is called:

Electromagnetic radiation with maximum wavelength is

The velocity of $\alpha-$rays is approximately