Question

A ray of light takes 10^-9 seconds to cross a glass slab of refractive index 1.5 the thickness of the glass slab is

Answer 1

The time taken by ray to cross glass slab  $[t] =10^-9\ seconds$

The refractive index of the glass slab  $\mu =1.5$

The refractive index of a glass is defined as-

                                           $\mu =\frac{c}{v}$

Here, c is the velocity of light in air.

          v is the velocity of light in glass

         $\mu\ is\ the\ refractive\ index\ of\ glass$

The velocity of light in glass slab is-

                                               $v=\frac{c}{\mu}$

                                                  $=\frac{3*10^8\ m}{1.5}$

                                                   $=2*10^8\ m/s$

The thickness of the glass slab [d] will be calculated as -

                                                    $d=v*t$

                                                       $=2*10^8\ m/s*10^-9\ s$

                                                       $=0.2 m$    [ans]

Answer 2

the answer is attached above