Electric Charges And Fields

An electric dipole experiences both a torque and a net force in a non-uniform electric field.

The net charge enclosed by the sphere is zero.

Figure shows a portion of a flat thin sheet, infinite in size with constant surface charge density (charge per unit area).
Let us draw a Gaussian surface (a cylinder) with one end on one side and other end on the other side and of cross-sectional area . Field lines will be tangential to the curved surface, so flux passing through this surfaces is zero. At plane surface electric field has same magnitude and perpendicular to surface. Hence, using,
ES =

The magnitude of electric field at an axial point M at a distance z from the origin is given by

For
and, magnitude of electric field at a equatorial point N at a distance y from origin (0, 0) is given by

For
For

According to Gauss's theorem electric flux ( ) through a closed surface S is
Electric flux ( )passes through the sphericaI Gaussian surface is independent of the radius of the paussian surface but depends only on the charge enclosed by the surface. On increasing the radius of Gaussian surface three times. there wouid be no effect on electric flux.

Let two charges are and and r is the distance between them. Then electrical force
F = ..(i)
If is increased by 10%, then

and is decreased by 10%, then

Then electrical force between them
F' =

..(ii)
From Eqs. (i) and (ii)
F'= 200 N