2. (15%) A gas has a dielectric constant , which depends on the wavelength ^ of the light

used in the measurement. It is given by

B

, = At

where A and B are constants. If the phase velocity and the group velocity of the light

wave are v and g respectively, express v,/v in terms of 1, A, and B.

2. (15%) A gas has a dielectric constant 6,. which depends on the wavelength A of the light used in the measurement. It is given by B Er=A+ where A and B are constants. If the phase velocity and the group velocity of the light wave are 1: and v9 respectively7 express 1:96,. / v in terms of A, A, and B