Electrical Capacitance—

Every conductor has the ability to hold the charge. When some charge is given to a conductor, its potential is also increased. This potential of conductor is directly proportional to the charge given to it.

Hence, Capacitance is defined as the charge required to increase the potential of the conductor by unity. It is a scalar quantity and its SI unit is farad.

Types of Material--

On the basis of their electrical conductivity materials are devided into two categories:

Potential Energy of an Electric Dipole, when placed in Uniform Electric Field--

Let us consider an Electric Dipole having dipole moment p is placed making an angle θ with external field . Then torque acting on the dipole is given by,

Electric potential Energy of a System of Charge—

The Electric Potential Energy of a system of point charges is defined as the work required to bring the charges constituting the system to their respective position from infinity.

Let we have three point charges q₁, q₂ and q₃ which are initially placed at infinity.

To bring the charge q₁ from infinity to its position, no work is Required.

When q₂ is brought to its position B, q₁ is already present,