What is effect of dielectric on the capacitance of a capacitor?

Define capacitance of a capacitor?

What is function of dielectric in capacitor?

What is function of dielectric in capacitor?

On what factors the capacitance of a capacitor depends?

Define capacitive reactance of a capacitor.

On inserting a dielectric between the plates of a capacitor, its capacitance is found to increase 5 times. What is the relative permittivity of the dielectric?

what is expression for the capacitive reactance of a capacitor. Also write the r.m.s. current through the capacitor.