IB Physics B.5 Current and Circuits Key Definitions

Electric circuits are systems where electric charge flows through a closed loop.

Electric current is the rate at which electric charge flows through a conductor.

An electric field is a region of space where a charge experiences a force.

Electric potential difference, or voltage, is the energy per unit charge required to move a charge between two points in an electric field.

The electromotive force (emf) is the work done per unit charge to move a charge completely around a circuit, including through the battery.

Internal resistance is the resistance within the battery itself, caused by the materials and chemical reactions inside it.

A light-dependent resistor (LDR) is a resistor whose resistance decreases as the intensity of light falling on it increases.

Ohm’s Law states that the current through a conductor is directly proportional to the potential difference across it, provided the temperature remains constant.

In a parallel circuit, resistors are connected across the same two points, providing multiple paths for current.

A potentiometer is a three-terminal resistor with a sliding contact that forms an adjustable voltage divider.

Power is the rate at which energy is transferred or converted.

The power dissipated in a circuit component is the rate at which energy is transferred.

Resistance is a measure of how much a material opposes the flow of electric current.

Resistivity is a fundamental property of a material that quantifies how strongly it resists the flow of electric current.

In a series circuit, resistors are connected end-to-end, forming a single path for current.

A thermistor is a resistor whose resistance changes with temperature.

Variable resistors are components that allow you to adjust the resistance in a circuit.