Chapter 24 Concepts - Electric Potential Flashcards
Define electric potential
a scalar quantity used to describe the electric potential energy
What quantities create electric potential energy?
charge and electric potential
Explain the directionality of electric potential
It is path independent because electric force is a conservative force
Discuss conservation of energy
If a charged particle moves through an electric field with no force acting on it other than the electric force, due to the field, mechanical energy is conserved
Discuss the work done by an external force
If some force in addition to the electric force acts on the particle, we can still have work due to that force, but can no longer associate it with potential energy because it may no longer be created by a conservative force.
Define equipotential surface
adjacent points that have the same electric potential; this can be either an imaginary or physical surface
What are the general rules for network and equipotential surfaces?
- There is no net work done on a charged particle by an electric field when the particle moves between points i and f on the same equipotential surface.
- Work must be zero if the initial electric potential equals the final electric potential.
- Because of the path independence of work (and potential and its energy), work is zero for ANY path connecting points i and f on a given equipotential surface regardless of whether that path lies entirely on that surface.
What is the relation between electric field and equipotential surfaces?
Equipotential surfaces are always perpendicular to electric field lines.
What is the relation between electric field and electric potential directionality?
If we move in the direction of the field, the potential decreases.
If we move in the opposite direction of the field, the potential increases.
The electric field vector points from higher potential to lower potential.
What is the relation between electric potential and electric charge directionality?
A positively charged particle produces a positive electric potential
A negatively charged particle produces a negative electric potential
What is the mathematical relation between electric field and electric potential?
The component of electric field (E) in any direction is the negative rate at which the electric potential changes with distance in that direction.
Discuss the potential energy directionality for a system of charged particles.
If there are two particles of the same sign charge, work and electric potential energy are positive
If there are two particles with opposite charges, work and potential energy are negative.
What is the total potential energy of a system?
The sum of the potential energies for every pair of particles in the system
What happens with isolated conductors and excess charges?
An excess charge placed on an isolated conductor will distribute itself on the surface of that conductor so that all points of the conductors – whether on the surface or inside – come to the same potential. This is true even if the conductor has an internal cavity and even if that cavity contains a net charge.
