Optical Fibre Principle for Engineering Physics and B Sc Physics Students

 

• In 1870 John Tyndall, a British physicist demonstrated that
• light can be guided along the curve of a stream of water.

Optical Fibre works on the principle of the Total Internal Reflection.

Total Internal Reflection:

When a light ray passes from a denser medium to a rarer medium then after a critical angle it reflects back in the denser medium. This phenomenon is called the total internal reflection of the light.

According to Snell's Law

$  n_1 \sin{\theta_{1}} = n_2 \sin{\theta_{2}}  $

For critical angle $\theta_{c}$ the angle of refraction is $\frac{\pi}{2}$ and the snell is

$\boxed{\sin{\theta_c} = \frac{n_2}{n1}}$

This is the critical angle for the total angle reflection.