OCR Physics Year 1 - Potential Difference, Resistance, and Power

A set of vocabulary flashcards defining fundamental concepts in electricity, including e.m.f., potential difference, resistance, component characteristics, resistivity, power, and energy calculations.

Electromotive Force (e.m.f.)

The energy gained per unit charge by charges passing through a supply when a form of energy is transferred to electrical energy carried by the charges. It is measured in volts ($\text{V}$) or joules per coulomb ($\text{J}\,\text{C}^{-1}$).

Potential Difference (p.d.)

The energy transferred per unit charge by the charges passing through a component (the work done per unit charge). It is measured in volts ($\text{V}$) or joules per coulomb ($\text{J}\,\text{C}^{-1}$).

Electronvolt

A derived unit of energy representing the energy transferred when one electron travels through a potential difference of one volt ($1\,\text{V}$).

Ohm's Law

States that the current through a conductor is directly proportional to the potential difference across it, provided that physical conditions, such as temperature, remain constant.

Electrical Resistance

The opposition to the flow of electric current, defined by the equation $R = \frac{V}{I}$, where $V$ is potential difference and $I$ is current. Its S.I. unit is the ohm ($\Omega$).

Ohmic Conductor

A conductor that obeys Ohm's law, exhibiting a direct proportionality between current and potential difference (such as a resistor at constant temperature).

Diode

A circuit component that allows electric current to pass in only one direction (the forward bias direction) and has almost infinite resistance in the reverse bias direction.

Light-Emitting Diode (LED)

A semiconductor diode that emits visible light when electric current flows through it in the forward bias direction.

Thermistor

An electrical component whose resistance changes based on its surrounding temperature.

Negative Temperature Coefficient (NTC) Thermistor

A type of thermistor whose resistance and resistivity decrease as its temperature increases.

Light-Dependent Resistor (LDR)

A component that has a high electrical resistance in the dark and a low resistance when light shines on it.

Resistivity

An intrinsic property of a material defined by the equation $\rho = \frac{RA}{l}$, where $R$ is resistance, $A$ is cross-sectional area, and $l$ is length. Its unit is $\Omega\,\text{m}$.

Electrical Power

The rate at which energy is transferred or work is done per unit time, measured in watts ($\text{W}$). Electrical equations for power include $P = IV$, $P = I^2 R$, and $P = \frac{V^2}{R}$.

Kilowatt-hour (kWh)

A unit of electrical energy defined as $1000\,\text{W}$ used for $3600\,\text{s}$, which is equal to $3.6 \times 10^6\,\text{J}$ ($3\,600\,000\,\text{J}$).