Unit 2: Conductors, Capacitors, Dielectrics

Electric field

Electric field

It is a vector quantity that describes the force experienced by a charged particle in an electric field.

zero

The electric field inside a conductor is _____, and any excess charge resides on the surface of the conductor.

surface of a conductor

The electric field on the ______ is perpendicular to the surface and is proportional to the surface charge density.

outside the surface

The electric field just ______ of a conductor is perpendicular to the surface and is equal to the electric field inside the conductor.

inside the surface

The electric field just _____ of a conductor is perpendicular to the surface and is equal to the electric field outside the conductor.

curved

The electric field on the surface of a conductor is strongest where the surface is most ____, and weakest where the surface is most flat.

Electric shielding

It is the process of reducing the electric field in a space by surrounding it with a conductive material.

Faraday cage

It is a type of electric shielding that completely surrounds a space with a conductive material, creating a barrier that prevents electromagnetic waves from entering or leaving the space.

Capacitor

An electronic component that stores electrical energy in an electric field. It consists of two conductive plates separated by a dielectric material.

Capacitance

It is the ability of a capacitor to store charge.

Parallel plate capacitor

It is a device that stores electrical energy in an electric field between two parallel conducting plates. It consists of two parallel plates separated by a dielectric material.

= εA/d

capacitance of a parallel plate capacitor

E = V/d

electric field between the plates of a parallel plate capacitor

U = (1/2)CV^2

energy stored in a parallel plate capacitor

Ceramic capacitors

These are the most commonly used type of capacitor.

Electrolytic capacitors

These are polarized capacitors that use an electrolyte as the dielectric.

Film capacitors

These are non-polarized capacitors that use a thin plastic film as the dielectric.

Tantalum capacitors

These are polarized capacitors that use tantalum metal as the anode.

Variable capacitors

These are capacitors whose capacitance can be adjusted.

E = 1/2 * C * V^2

energy stored in a capacitor

Dielectrics

These are materials that do not conduct electricity easily.

Polar dielectrics

These have a permanent dipole moment due to the presence of polar molecules.

Non-polar dielectrics

They do not have a permanent dipole moment. They are made up of non-polar molecules and do not align themselves in an electric field.

Dielectric strength

It is the maximum electric field that a dielectric material can withstand before it breaks down and conducts electricity. It is measured in volts per meter (V/m).