AP Physics C E&M: Capacitance

capacitance, C

The ratio of the maximum charge that can be stored in a capacitor to the applied potential difference across its plates.

capacitor

device that stores electrical charge and electrical energy

dielectric

insulating material used to fill the space between two plates

dielectric breakdown

phenomenon that occurs when an insulator becomes a conductor in a strong electrical field

dielectric constant

factor by which capacitance increases when a dielectric is inserted between the plates of a capacitor

dielectric strength, κ

critical electrical field strength above which molecules in insulator begin to break down and the insulator starts to conduct

energy density

energy stored in a capacitor divided by the volume between the plates

induced electric-dipole moment

dipole moment that a nonpolar molecule may acquire when it is placed in an electrical field

induced electrical field

electrical field in the dielectric due to the presence of induced charges

induced surface charges

charges that occur on a dielectric surface due to its polarization

parallel combination

components in a circuit arranged with one side of each component connected to one side of the circuit and the other sides of the components connected to the other side of the circuit

parallel-plate capacitor

system of two identical parallel conducting plates separated by a distance

series combination

components in a circuit arranged in a row one after the other in a circuit

Farad, F

The SI unit for capacitance.

electrostatic potential energy, U

As the capacitor is being charged, the electrical field builds up. This type of energy is stored within the capacitor due to the presence of the strengthened electric field.

neutral

When battery terminals are connected to an initially uncharged capacitor, the battery potential difference moves a small amount of charge of magnitude Q from the positive plate to the negative plate. The capacitor remains __________ overall, but with charges +Q and −Q residing on opposite plates.

geometry, material

Capacitance is a function only of the __________ and what __________ fills the space between the plates of this capacitor.

constant

The capacitance is independent of the maximum charge stored in the capacitor or the potential difference across the plates. If the charge changes, the potential changes correspondingly so that ratio defining capacitance remains __________.

equivalent, series, parallel

Multiple connections of capacitors behave as a single __________ capacitor. The total capacitance of this equivalent single capacitor depends both on the
individual capacitors and how they are connected. Capacitors can be arranged in two simple and common types of
connections, known as __________ and __________, for which we can easily calculate the total capacitance.

charge

All capacitors of a series combination have the same __________. This occurs due to the conservation of __________ in the circuit.

potential difference

Capacitors connected in parallel have the same __________ across their plates.

field

As the capacitor is being charged, the electrical __________ builds up. When a charged capacitor is disconnected from a battery, its energy remains in the field in the space between its plates.

dielectric

The capacitance of an empty (vacuum) capacitor can be increased by a factor of κ when we insert a __________ material to completely fill the space between its plates.

reciprocals

When several capacitors are connected in a series combination, the reciprocal of the equivalent capacitance is the sum of the __________ of the individual capacitances.

sum

When several capacitors are connected in a parallel combination, the equivalent capacitance is the __________ of the individual capacitances.

equivalent

When a network of capacitors contains a combination of series and parallel connections, we identify the series and
parallel networks, and compute their __________ capacitances step by step until the entire network becomes reduced to one equivalent capacitance.

work, field

The energy stored in a capacitor is the __________ required to charge the capacitor, beginning with no charge on its plates.
The energy is stored in the electrical __________ in the space between the capacitor plates. It depends on the amount of electrical charge on the plates and on the potential difference between the plates.

constant

Each dielectric material has its specific dielectric __________.

field

When a dielectric is inserted between the plates of a capacitor, equal and opposite surface charge is induced on the two faces of the dielectric. The induced surface charge produces an induced electrical __________ that opposes the field of the free charge on the capacitor plates. This reduces the potential difference across the plates and increases the capacitance as a result.