Page 12 - 10-phy-13 Electrostatics

13. Electrostatics eLearn.Punjab

In order to find the value of electric intensity at a point in the field, of charge +q, we place a test

charge qo at that point (Fig. 13.11). If F is the force acting on the test charge qo, the electric field
intensity would be given by

Physics Insight

The electric field intensity at any point is defined as the
force acting on a unit positive charge placed at that point.

SI unit of electric intensity is N C-1.
If the electric field due to a given arrangement of charges is known
at some point, the force on any particle with charge q placed at
that point can be calculated by using the formula:

Electric intensity being a force is a vector quantity. Its direction is Variation of magnitude of Coulomb’s
the same as that of the force acting on the positive test charge. If force between two opposite
the test charge is free to move, it will always move in the direction
of electric intensity. charges of different magnitudes.

Animation 13.13: Electric field Animation 13.14: Electric field intensity
Source and Credit Source and Credit

For Your Information

Electric field lines for two opposite and Electric field lines for two positive point Electric field lines for two negative
point charges.
equal point charges. charges.
V: 1.1
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