Physics B.5 Currents and Circuits

Direct current (dc)

rate of flow of charge carriers.

Electric potential difference

the work done per unit charge in moving a unit positive charge between two points.

Electrical conductor

a material in which charge carriers can flow easily

Electrical insulator

a material in which charge carriers cannot flow easily

Electrical resistance

a measure of how difficult current can pass through an electrical component.

Resistivity

the property of a material that measures how strongly it resists current

Ohm’s law

the electric potential difference across a conductor is directly proportional to the current flowing through it at constant temperature

Electrical power

the rate of transfer of electrical energy

Series circuit

All components are on one loop of wire and the same current flows through all components.

Parallel circuit

components are connected with different branches for the current to flow through, potential difference is constant.

Electromotive force (emf)

The amount of energy transferred to each unit of charge.

Internal resistance

The resistance inside a cell that causes the electric potential difference across a cell to be less than its emf when the cell is in series with a resistor.

voltmeters

measures electric potential difference, connected to either side of s component in parallel. Ideal voltmeter has infinite resistance

ammeters

measures the rate of flow of charge carriers, connected within the flow of electrons in the circuit in series. Ideal ammeter has 0 resistance

Temp increases

Resistance increases