Assertion: In the absence of an external electric field, the dipole moment per unit volume of a polar dicletric is zero.
Reason : The dipoles of a polar diclectric are randomaly oriented.

Options

A. If both assertion and reason are ture and reason is the correct explanation of assertion.
B. If both assertin and reason are ture but reason is not the correct explanation of assertion .
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

A

Explanation

There are polar and non polar dielectric materials. The molecules of a polar dielectric have a permanent dipole moment . However due to random orientations net dipole moment is zero. If there is no external electric field , there is no polarishation.