Field Strength or Field Intensity or Electric Intensity

Field Strength or Field Intensity or Electric Intensity :

Electric intensity at any point within an electric field may be defined in either of the following three ways :
(a) It is given by the force experienced by a unit positive charge placed at that point. Its direction is the direction along which the force acts. Obviously, the unit of E is newton/coulomb (N/C).

For example, if a charge of Q coulombs placed at a particular point P within an electric field instances a force of F newton, then electric field at that point is given by

E = F/Q N/C

The value of E within the field due to a point charge can be found with help of Coulomb’s laws.

Suppose it is required to find the electric field at a point A situated at a distance of d meters from a charge of Q coulombs. Imagine a positive charge of one coulomb placed at that point (Figure given below).

or in vector notation,

(b) Electric intensity at a point may be defined as equal to the lines of force passing normally through a unit cross-section at that point. Suppose, there is a charge of Q coulombs. The number of

lines of force produced by it is Q/ε. If these lines fall normally on an area of A m2 surrounding the point, then electric intensity at that point is

The unit of E is volt/metre.

In other words, E is equal to the rate of fall of potential in the direction of the lines of force.

Obviously, the unit of E is volt/meter.

It may be noted that E and D are vector quantities having magnitude and direction.

∴ In vector notation,

Difference between electric field and electric field strength?

The Basic Difference between electric field and electric field intensity is that, The electric field is a region around a charge in which it exerts an electrostatic force on other charges. While the strength of the electric field at any point in space is called electric field intensity. It is a vector quantity

What is electric field and electric field intensity?

The space around an electric charge in which its influence can be felt is known as the electric field. The electric field Intensity at a point is the force experienced by a unit positive charge placed at that point. Electric Field Intensity is a vector quantity.

Formula: Electric Field = F/q.

Read article – Units of Resistivity

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