1.8 ELECTRIC FIELD

DEFINITION OF ELECTRIC FIELD           
"The electric field due to a charge Q at a point in space may be defined as the force that a unit positive charge would experience if placed

at that point."

The charge Q, which is producing the electric field, is called a source charge and the charge q, which tests the effect of a source charge, is called a test charge
 The direction of the field is taken to be the direction of the force it would exert on a positive test charge. The electric field is radially outward from a positive charge and radially in toward a negative point charge.




ELECTRIC FIELD DUE TO POINT CHARGE

The electric field of a point charge can be obtained from Coulomb's law: The electric field is radially outward from the point charge in all directions. The circles represent spherical equipotential surfaces.

The electric field from any number of point charges can be obtained from a vector sum of the individual fields. A positive number is taken to be an outward field; the field of a negative charge is toward it.