Answer:
The time of short pulse of light beam is 
Explanation:
Given that,
A beam of light from a laser illuminates a glass.
Suppose, the length of piece is 
Index of refraction is 2.83.
We need to calculate the speed of light pulse in glass
Using formula of speed

Put the value into the formula


We need to calculate the time of short pulse of light beam
Using formula of velocity


Put the value into the formula


Hence, The time of short pulse of light beam is 