Energy density is the amount of energy stored in a given system or region of space per unit volume or mass. we=21D.EJ/m2 Energy density in an isotropic medium: we=21ϵ∣E∣2(∵D=ϵE)
Electric potential (V) at a point is defined as the amount of work done in bringing a unit positive charge from infinity to that point. Unit of potential is 1V=1JC−1. V=QW Note: Potential is taken to be zero at infinity and at ground.
Work done by a given charge
Work done by a charge to move through a potential difference V is given by W=Q(Vf−Vi). Where Vf = Final potential and Vi = Initial potential
Unit of potential difference
The S.I Unit of potential difference is volt (V). 1 volt =One volt is the potential difference between two points in a current carrying conductor when 1 joule of work is done to move a charge of 1 coulomb from one point to the other. 1Volt=1Coulomb1Joule The potential difference is measured by an instrument called voltmeter.