Question

A charged capacitor stores energy U. Without connecting this capacitor to anything, dielectric having dielectric constant K is now inserted between the plates of the capacitor, completely filling the space between them. How much energy does the capacitor now store?

Answer 1

U / K

Step-by-step explanation:

The energy stored in the capacitor is given by

`U=(q^(2))/(2C)`

where, q be the charge and C be the capacitance of the capacitor.

If a dielctric is inserted beteen the plates of capacitor having dielctric constant K, the new capacitance is C' = KC

The charge will remain same

The new energy stored is

`U'=(q^(2))/(2C')`

`U'=(q^(2))/(2KC)`

U' = U / K

So, the energy reduces by the factor of K.