Electric Potential
- Gravitational Force & Potential Energy
- conservative force
- work done is path independent
- allows definition of potential energy
- Coulomb Force
- conservative force
- can define potential energy
- Electrical Potential Energy
- Assume uniform Electric Field (not necessary)
- Put charge in field
- move charge in direction of field
- field does work
- Conservative Force
- Work-Energy Theorem
- If the force is provided by an electric field the above equation becomes
- Electric Potential
- Change in Potential Energy
- depends on size of charge being moved
- similar to grav. pot. energy depending on mass
- Want quantity that is independent of charge
- divide by charge
- electric potential
- scalar quantity
- measured in J/C = Volts = V
- related to electric field
- new units for electric field
- Electric Potential has units energy per unit charge
- Positive Charge (Denergy)
- in same direction as E
- from high potential to low potential
- loses potential energy
- gains kinetic energy
- in direction opposite to field
- from low potential to high potential
- gains potential energy
- loses kinetic energy
- Negative Charge (Denergy)
- in same direction as E
- from high potential to low potential
- gains potential energy
- loses kinetic energy
- in direction opposite to field
- from low potential to high potential
- loses potential energy
- gains kinetic energy
- Examples
- Potential due to Point Charges
- The electric field due to a point charge points directly away from a point
charge (+) or directly toward (-). The only contribution to the scalar product
will come when we are moving in the direction of changing r. "sideways"
motion will not contribute
- pick a reference point, V = 0 , at rA = infinity
- Superposition Principle applies to electric potential
, Scalar quantity; rules of arithmetic addition
- Potential Energy of a Second Charge
- U = qV (Work necessary to bring charge in from infinity)
- Multiple Charges
- Examples
