In He-Ne laser, population inversion is achieved by

For making a capacitor it is better to have a dielectric having

A. High permittivity

B. Low permittivity

C. Permittivity same as that of air

D. Permittivity which is neither high nor low

Which inductor is linear?

A. Air cored

B. Cast iron cored

C. Sheet steel cored

D. Iron alloy cored

As the viscosity of a liquid increases, the relaxation time

A. Remains constant

B. Increases

C. Decreases

D. First decreases then increases

The materials which become polarized on the application of mechanical stress are called piezoelectric.

A. True

B. False