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

The frequency of a radio wave from Mars to Earth is $6 \times 10^3 \, s^{-1}$. If the distance between them is $8 \times 10^7 \, km$,how much time will it take?

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

Which of the following does not contain material particles?

$X$-rays are produced due to

Which of the following travels with the speed of light?