(a) Speed of light in glass, v = $\frac{c}{\,\mu_g^{a}}$ = $\frac{3 \times 10^{8}}{1.5}$ = 2 × $10^{8}\text{ms}^{-1}$ (b) Yes, speed of light in glass depends upon the colour of light (i.e., λ). Thus, speed of light is different for red and violet colours. As $\mu_V$ > $\mu_R$, so, $l_V$ < $l_R$, hence, $v_V$ < $v_R$ Speed of red colour is more than violet colour light in glass