Capacitor

Definition

A capacitor is an electrical component that stores energy in the form of an electric field, created by a pair of conductors separated by an insulating material. The ability to store charge is measured in farads (F).

5 Must Know Facts For Your Next Test

1. The capacitance (C) of a capacitor is defined as $C = \frac{Q}{V}$, where Q is the charge stored and V is the voltage across the capacitor.
2. Capacitors can be connected in series or parallel, with different rules for calculating equivalent capacitance: for series $\frac{1}{C_{eq}} = \frac{1}{C_1} + \frac{1}{C_2} + ...$ and for parallel $C_{eq} = C_1 + C_2 + ...$.
3. The energy (U) stored in a capacitor is given by $U = \frac{1}{2}CV^2$.
4. Dielectrics are materials placed between the plates of a capacitor to increase its capacitance by reducing the electric field strength.
5. In DC circuits, capacitors initially act like short circuits when charging and open circuits once fully charged.

Review Questions

• What formula defines capacitance?
• How do you calculate the equivalent capacitance for capacitors in series and parallel?
• What effect does inserting a dielectric material into a capacitor have on its capacitance?

Related terms

Electric Field: A field around charged particles that exerts force on other charged particles, measured in volts per meter (V/m).

Resistor: A component that resists the flow of electric current, causing a drop in voltage. Measured in ohms (Ω).

Dielectric: An insulating material placed between the plates of a capacitor which increases its overall capacitance.