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Dipole in uniform electric field:
Net force on a dipole in a uniform electric field is zero.
Torque , torque is maximum when the dipole is perpendicular to the field and minimum when the dipole is parallel or antiparallel to the field.
Dipole in non-uniform electric field:
The net force depends on
Orientation of the dipole, dipole moment of the dipole and how rapidly the field varies.
The product of magnitude of electric field and surface area A perpendicular to the field is called electric flux . depends on both field pattern and surface. The net flux is directly proportional to the net number of lines leaving the surface.
Electric flux through a closed surface S is given by , where q is the charge enclosed by surface S.
The net field is due to all charges present inside and outside the Gaussian surface. No net flux is contributed by the charges present outside the Gaussian surface because the number of E-lines coming into the surface is equal to the number of E-lines going out of the surface.
Electric field due to a charged isolated plate:
The electric field due to a charged isolated plate is twice the field due to a plane sheet of charge . The electric field due to an infinitely charged plate does not depend on the distance from the plate.
The potential at a point P is given by , which is equal to the external work done per unit positive charge in shifting slowly from infinity to this point.
In the direction of electric field, the potential always decreases.
Potential is a scalar quantity. Its SI unit is volt.
An equipotential surface is a surface with constant value of potential at all points on the surface. The equipotential surface of a single point charge are concentric spherical surfaces centred at the charge. For uniform electric field, equipotential surfaces are planes normal to the plane of the electric field.
Potential energy of a system of charges:
For two charges,
For three charges,
For discreet system of charges,
General formula for calculating potential energy: U = qV, where V is the potential at a point of some continuous body (ring, disc, solid sphere etc.).
Finding electric field from electric potential:
Earthing of a conductor:
On earthing a conductor, the charge on the conductor varies and the potential of the conductor becomes zero.
Charge distribution on a conductor surface:
The charge distribution takes place on the surface of the conductor in such a way that the product of charge density and the radius of curvature r at any point on the conductor is constant, i.e.
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Queries asked on Sunday and after 7 pm from Monday to Saturday will be answered after 12 pm the next working day.
4 charges are placed on corners of a square having side of 5cm. If Q is one microcoulomb, then electric field intensity at center will be?
A charged oil drop is kept at rest between 2 horizontal plates by applying electric filed.If electric field is momentarily switched on and off. Then what will be the position of the oil drop
ye solve krna h sir