DO YOU HAVE THE ENGLISH TRANSLATION?
The phenomenon that is observed when an incident ray travelling in a slower medium strikes the boundary of a faster medium with an angle greater than the critical angle is known as total internal reflection.
Total internal reflection results in the the ray being reflected within the medium, instead of leaving it after undergoing diffraction. This phenomenon is the working principle of optical fibers.
This is the Law of Horizontality
Answer:
Force, 
Explanation:
Given that,
Charges on pith balls, 
Distance between balls, d = 9 cm = 0.09 m
Let F is the repulsive force between two pith balls. We know that the repulsive force between two charges is given by :


F = 0.000871 N
or

So, the repulsive force between the pith balls is
. Hence, this is the required solution.