Electrical resistance

Electrical resistance quantifies how strongly a material or component opposes electric current. It is measured in ohms and relates voltage to current through Ohm’s law for ohmic components.

Ohm’s law: A relation stating that voltage across an ohmic component equals its current multiplied by its resistance. It defines resistance through the voltage-to-current ratio when that ratio remains constant.
Electric current: The rate at which electric charge passes through a surface. Resistance describes opposition to this flow of charge.
Resistor: A two-terminal component designed to provide a specified electrical resistance. Resistors provide controlled resistance in practical circuits.
Electrical conductance: A measure of how readily a component conducts electric current, equal to the reciprocal of resistance. Conductance expresses the same behavior in the opposite direction.
Electrical resistivity: An intrinsic material property relating electric field to current density. It separates a material’s contribution to resistance from a component’s shape.
Voltage: The electric potential difference between two points, equal to energy transferred per unit charge. Voltage supplies the electrical push compared with current in defining resistance.
Voltage divider: A circuit that produces an output voltage from a portion of its input voltage using series impedances. Resistor ratios set the output voltage in the common resistive divider.
Superconductivity: A state of matter with zero DC electrical resistance below a material-specific critical temperature. It is a distinct limiting case in which ordinary resistance vanishes.
Drift velocity: The average velocity acquired by charge carriers in a material under an applied electric field. Resistance arises as scattering limits carriers’ net motion through a conductor.
Electric charge: A fundamental property of matter that produces and responds to electromagnetic forces. Moving charge constitutes current, the quantity resistance opposes.

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