Current and Circuits - Summary Notes

Electric current

A flow of charged particles.

Conventional current

The direction a positive test charge moves.

Electric Potential Difference

Maintained by pumping charged particles from lower to higher potential; requires an external energy source.

Voltaic/Galvanic cells (batteries)

Convert chemical energy to electrical energy.

Photovoltaic cells (solar cells)

Convert light energy to electrical energy

Electric Circuits

A closed loop allowing electric charges to flow; includes a charge pump and a device that reduces potential energy.

Electric current (I)

The rate of flow of electric charge, I = q/t.

Ampere (A)

SI unit for current, 1 A = 1 coulomb/second.

Resistance (R)

Determines how much current flows, R = \Delta V/I, measured in ohms (Ω).

Ohm’s law

Devices with constant resistance independent of potential difference.

Resistors

Used to control the current in circuits.

Potentiometer

A variable resistor is used to control the current in circuits.

Parallel Connection

Current has multiple paths.

Series Connection

Current has only one path.