Field of force

Field of force

The space or region around a point charge with in which another charge experience a force is called electric field.”

Origin of force:

Newton’s universal gravitational law and coulomb’s law help us to calculate the magnitude and direction of the gravitational and electric forces. However one may question.

What are the origins of these force?

How these forces transmitted from one mass to another or form one charge to another.

The answer to (1) is still unknown, that is why these forces are called basic forces of nature.

Micheal Faraday’s concept of an electric field:

To explain the transmission of electric forces Micheal Faraday’s introduced the concept of an electric field. According to Faraday it is intrinsic property of nature that an electric field exists in space around an electric charge.

A charge produces an electric field in the space surrounding it in the form of a sphere as shown below.

This field is tested only by taking another charge in field.

Electric field intensity:

The magnitude of force experienced by a unit positive charge placed at a point in the electric field is called electric field strength or electric intensity of that point.”

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Explanation:

Consider a charge q which produces a field. When a charge q is placed in the field the charge q interacts with q to produce an electric force. Then electric field intensity is given by:

Where F is the force experienced by positive test charge qo.The test charge qo should be very small so that it does not disturb the field to be measured. The strength of field is proportional to density of dots.

Unit:

Electric field is force per unit charge thus S.I unit are NC-1

It is vector quantity and its direction is in the direction of force.

Electric intensity due to a point charge:

Consider a point charge q placed in vaccum producing its own electric field. A test charge qo is placed in the field at a distance ‘r’ from the point charge.Then the force experienced by test charge qo due to charge q according to coulomb’s force is given by.google.com, , DIRECT, f08c47fec0942fa0

Where r ̂is a unit vector directed from the point charge q to test charge qo But electric intensity at that point where qo is placed is given by

The magnitude of electric intensity due to a point charge is given by

Electric field intensity depends on

Magnitude of charge

Medium

Distance from charge

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