Chapter 3 Review
Key Terms
electric dipole
system of two equal but opposite charges a fixed distance apart
electric dipole moment
quantity defined as for all dipoles, where the vector points from the negative to positive charge
electric potential
potential energy per unit charge
electric potential difference
the change in potential energy of a charge moved between two points, divided by the charge.
electric potential energy
potential energy stored in a system of charged objects due to the charges
electron-volt
energy given to a fundamental charge accelerated through a potential difference of one volt
electrostatic precipitators
filters that apply charges to particles in the air, then attract those charges to a filter, removing them from the airstream
equipotential line
two-dimensional representation of an equipotential surface
equipotential surface
surface (usually in three dimensions) on which all points are at the same potential
grounding
process of attaching a conductor to the earth to ensure that there is no potential difference between it and Earth
ink jet printer
small ink droplets sprayed with an electric charge are controlled by electrostatic plates to create images on paper
photoconductor
substance that is an insulator until it is exposed to light, when it becomes a conductor
Van de Graaff generator
machine that produces a large amount of excess charge, used for experiments with high voltage
voltage
change in potential energy of a charge moved from one point to another, divided by the charge; units of potential difference are joules per coulomb, known as volt
xerography
dry copying process based on electrostatics
Key Equations
| Potential energy of a two-charge system | |
| Work done to assemble a system of charges | |
| Potential difference | or |
| Electric potential | |
| Potential difference between two points | |
| Electric potential of a point charge | |
| Electric potential of a system of point charges | |
| Electric dipole moment | |
| Electric potential due to a dipole | |
| Electric potential of a continuous charge distribution | |
| Electric field components | |
| Del operator in Cartesian coordinates | |
| Electric field as gradient of potential | |
| Del operator in cylindrical coordinates | |
| Del operator in spherical coordinates |
Summary
3.1 Electric Potential Energy
- The work done to move a charge from point to in an electric field is path independent, and the work around a closed path is zero. Therefore, the electric field and electric force are conservative.
- We can define an electric potential energy, which between point charges is , with the zero reference taken to be at infinity.
- The superposition principle holds for electric potential energy; the potential energy of a system of multiple charges is the sum of the potential energies of the individual pairs.
3.2 Electric Potential and Potential Difference
- Electric potential is potential energy per unit charge.
- The potential difference between points and , ,