First slide

Ray optics

Question

A light ray from air is incident (as shown in figure) at one end of a glass fiber (refractive index m = 1.5) making an incidence angle of 60^o on the lateral surface, so that it undergoes a total internal reflection. How much time would it take to traverse the straight fiber of length 1 km(nearly)

Moderate

A

3.33 $μ$ sec
B

6.67 $μ$ sec
C

3.85 $μ$ sec
D

5.77 $μ$ sec

Solution

$\Rightarrow \sin 60^{o} = \frac{1}{x} \Rightarrow \frac{1}{x} = \frac{\sqrt{3}}{2}$
dist travelled by ray of light
$d = \frac{x}{1} x 1 km = \frac{2}{\sqrt{3}} x 10^{3} m \Rightarrow t = \frac{d}{v} = \frac{d}{(C_{0} / μ)} = \frac{dμ}{C_{0}}$
$\Rightarrow t = \frac{\frac{2}{\sqrt{3}} x 10^{3} x \frac{3}{2}}{3 x 10^{8}} = 5.77 μs$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App