NAGALAND Class 12-science Physics Electrostatic Potential and Capacitance
Electrostatic Potential1. The potential energy per unit charge at a point in an electric field is called the electric potential at the point.
2. The electric potential difference between two points in an electric field is equal to the difference in potential energy per unit charge between the two points.
3. The component of andnbsp;andnbsp; in any direction is the negative of the rate of change of the electric potential with distance in that direction.
Equipotential SurfacesElectric field lines are always perpendicular to the equipotential surfaces.
Work done in moving a charge from along an equipotential surface=0
Equipotential surfaces due to Point charge: Concentric spheres.
Electrostatic Potential EnergyDefinitionand calculation of electrostatic potential energy. Identify the electrostatic potential energy of a system of charges placed in an external field.
Electrostatics of ConductorsThe electric field inside a conductor is zero.
Any induced or excess charge must reside on the outer surface of the conductor. This is true even for conductors with cavity so long as there is no charge inside the cavity.
The entire volume of the conductor is at the same potential or is equipotential because the electric field inside the conductor is zero.
Just outside the conductor, the electric field is normal or perpendicular to the surface.
CapacitorsDefine the meaning of capacitance. Study how a capacitor stores charge and energy. Learn to quantify the capacitance in terms of charge Q and potential V.
Combination of CapacitorsThe energy U required to charge a capacitor C to a potential difference V and a charge Q is equal to the energy stored in the capacitor. This energy can be thought of as residing in the electric field between the conductors.
The reciprocal of the equivalent capacitance of a series combination equals the sum of the reciprocals of the individual capacitances.
The equivalent capacitance of a parallel combination equals the sum of the sum of the individual capacitances.
Electrostatics of DielectricsA dielectric reduces the electric field in a given region.
Dielectrics are of 2 types: Polar and Non-Polar. Polar molecules have permanent dipole moments, whereas the non-polar molecules have zero dipole moment.
The dipole moment per unit volume of the dielectric is quantified as polarization.
The ratio of the applied electric field (Eo) to the net field (E) inside the dielectric is known as dielectric constant of the material.