Explain the reason for the formation of a spectrum.

Write examples of a continuous spectrum.

What are the different regions of the electromagnetic spectrum?

The ratio of the energy of a photon with wavelength $3000 \ \mathring{A}$ to that of a photon with wavelength $6000 \ \mathring{A}$ is:

Calculate the frequency and wave number of a photon with a wavelength of $3.6 \ \mathring{A}$.

Arrange the following types of radiations in increasing order of frequency: $(a)$ radiation from microwave oven,$(b)$ amber light from traffic signal,$(c)$ radiation from $FM$ radio,$(d)$ cosmic rays from outer space,and $(e)$ $X$-rays.