Introduction to Electrical Properties

Electrical properties include the response of a material for an applied electric field.

Resistivity

Measure of how strongly a material opposes the flow of electric current.

Resistance

Not a property of a material.

Conductivity

Reciprocal of the electrical resistivity.

Depends on:

• Number of available charge carriers
• Material’s composition
• Material’s structure
• Temperature
• Impurities

Electron Mobility

When an electrical field is applied, the free electron in a solid can be accelerated under force applied by electric field.

Force acting on a single electron is . Here:

• - charge of electron
• - electric field strength

In a solid, the electrons are scattered by obstacles such as atom cores/imperfections etc. The electrons have a net drift at the direction opposite to the electric field

Drift Velocity

Average velocity attained by charge carriers accelerated in an electric field.

Note

In a conductor, such as a wire, the charge carriers are typically electrons. Due to thermal motion, electrons in a conductor have random velocities in all different directions.

Carrier Concentration

Number of charge carriers per unit volume. Usually denoted by .

Current Density

Amount of electric current flows through a unit area.

Here:

• - carrier concentration
• - charge on a single charge carrier
• - drift velocity
• - conductivity
• - applied electric field

Carrier Mobility

Denoted by .