Please solve question no.1.

Dear Student

R e f r a c t i v e I n d e x = \frac{S p e e d o f l i g h t i n a i r}{S p e e d o f l i g h t i n m e d i u m} S p e e d o f l i g h t i n g l a s s = \frac{S p e e d o f l i g h t i n a i r}{R e f r a c t i v e I n d e x o f g l a s} S p e e d o f l i g h t i n g l a s s = \frac{3 \times 10^{8} m / s}{1.5} = 2 \times 10^{8} m / s

Regards