A curved glass piece of uniform thickness has a zero power. Why?

SO_3 has zero dipole moment. Why ?

Light travels through a glass plate of thickness t and having a refractive index mu .If c is the velocity of light in vacuum,the time taken by the ligth to travel this thickness fo glass is

At zero kelvin, a piece of Germanium behaves as:

A copper rod of diameter 1 cm and length 8 cm is drawn into a wire of length 18 m of uniform thickness. Find the thickness of the wire.

Why is the middle piece of human sperm considered as power house of cell ?

Why middle piece of sperm called its power house ?