Download Lecture ( 7 ) Electric Potential and Capacitance

Lecture ( 7 )
Electric Potential and Capacitance
2.7 Electric Potential ( V )
The work per unit of charge required to move a charge from a reference point to a
specified point, measured in joules per coulomb or volts. The static electric field is the
negative of the gradient of the electric potential.
Equipotential Surfaces
Electric Pontential and Electric Potential Energy
The change in potential energy of a charge ( q ) moving from point (i) to point (f ) is equal
to the work done by the applied force , which is equal to minus the work done by the electric
field , which is related to the difference in electric potential:
We move a proton from point (i) to point (f) in uniform electric field ,as shown.
Electric Potential of a Point Charge
Note: if ( Q ) were a negative charge ,( V ) would be negative.
Electric Potential of Many Point Charges
Electric potential is a SCALAR not vector , therefore just calculate the potential due to each
individual point charge, and add together ( Make sure you get the SIGNS correct )
2.8 Capacitance
Energy is store in the electric field that exists between the plates when the capacitor is
charged.
Conducting plates
Dielectric
Stored Energy