Question

A laser beam enters a 12.0 cm thick glass window at an angle of 33.0° from the normal. The index of refraction of the glass is 1.41. At what angle from the normal does the beam travel through the glass? How long does it take the beam to pass through the plate?

Answer 1

Answer:

The time is 0.563 ns.

Explanation:

Given that,

Index of refraction of glass = 1.41

Distance = 12.0 cm

Angle = 33.0°

We need to calculate the refraction angle

Using Snell's law

$n_{1}\sin\theta=n_{r}\sin\theta$

put the value into the formula

$1\times\sin33=1.41\sin\theta$

$\sin\theta=\dfrac{1\times\sin33}{1.41}$

$\theta=22.71^{\circ}$

We need to calculate the velocity of beam in glass

Using formula of velocity

$v=\dfrac{c}{n}$

Put the value into the formula

$v=\dfrac{3\times10^{8}}{1.41}$

$v=2.13\times10^{8}\ m/s$

We need to calculate the time

Using formula of distance

$v=\dfrac{d}{t}$

$t=\dfrac{12.0\times10^{-2}}{2.13\times10^{8}}$

$t=5.63\times10^{-10}\ sec$

$t=0.563\times10^{-9}\ sec$

$t=0.563\ ns$

Hence, The time is 0.563 ns.