Question

Define capacitance of a capacitor. Derive expression for stored energy between plates of parallel capacitor. Show that energy-density between plates of the capacitor can be expressed us 1/2 ∈0 E2, when E = Electric field between plates.

Answer 1

Capacitance- lt is the ability of a body to store an electric charge. We consider a parallel plate capacitor. Let every plate has area A and placed at a distance d. when capacitor is charged with voltage V, then stored energy is-

U = 1/2 CV2...... (i)

But capacitance of parallel plate capacitor is C = ∈0A/d .......(ii)

and potential difference, V = Ed

Putting the value of.V in equation (i)