Solution:

(a) Expression of the relation between the speed of light (c) in the air and in glass (v) is as follows –

μ = c / v

or we can write

c = 1.5 v

(b) Let the wavelength of light in glass be given by λ¹

Then, using the expression =>

μ = λ / λ¹

Therefore, wavelength of light in glass λ¹ = λ / 1.5