Potential Difference - Introduction

Description:

To understand the potential difference between two points and the potential of a point, take two points say A,B in an electric field. A unit test charge at point B is supposed to be moved at point A. The charge ‘q’ at B will experience a force (F=qE) in the direction of electric field, but the displacement will be in the direction opposite to that of force. In order to move the charge opposite to that of force, some work has to be done by applying energy.

When work is done on unit charge to displace it from one point to another this is called potential difference. It is symbolized by (V)

Work done on unit charge = V_A-V_B.....(1)

V_A-V_B is read as potential difference between A to B.

Let the work done to move charge q from B to A = W.

So, the work done to move a unit charge from B to A = W / q .....(2)

Putting (2) in (1) we get −

VA - VB = W/q

If the charge is moved to a very small distance, then a small work will be done by the charge(q) will be dW

So, the small work done by a unit charge from B to A = dW / q

Then, the potential difference due to small work done by unit charge will be −

dV = dW / q

The difference of Potential between two points in an electric field gives the potential difference. If the potential of any one point becomes zero, gives the potential of other point.

Note

• If the charge is taken to be 1 unit then the potential difference will be equal to work done.

• Potential difference is a scalar quantity having no direction.

• Potential difference is the characteristic between measurement of two points, depending on the strength of electric field.