Chapter 4 Review
Key Terms
capacitance
amount of charge stored per unit volt
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
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
Key Equations
| Capacitance | |
| Capacitance of a parallel-plate capacitor | |
| Capacitance of a vacuum spherical capacitor | |
| Capacitance of a vacuum cylindrical capacitor | |
| Capacitance of a series combination | |
| Capacitance of a parallel combination | |
| Energy density | |
| Energy stored in a capacitor | |
| Capacitance of a capacitor with dielectric | |
| Energy stored in an isolated capacitor with
dielectric |
|
| Dielectric constant | |
| Induced electrical field in a dielectric |
Summary
4.1 Capacitors and Capacitance
- A capacitor is a device that stores an electrical charge and electrical energy. The amount of charge a vacuum capacitor can store depends on two major factors: the voltage applied and the capacitor’s physical characteristics, such as its size and geometry.
- The capacitance of a capacitor is a parameter that tells us how much charge can be stored in the capacitor per unit potential difference between its plates. Capacitance of a system of conductors depends only on the geometry of their arrangement and physical properties of the insulating material that fills the space between the conductors. The unit of capacitance is the farad, where
4.2 Capacitors in Series and in Parallel
- When several capacitors are connected in a series combination, the reciprocal of the equivalent capacitance is the sum of the reciprocals of the individual capacitances.
- When several capacitors are connected in a parallel combination, the equivalent capacitance is the sum of the individual capacitances.
- When a network of capacitors contains a combination of series an