6. Electricity Definitions Flashcards
Define ammeter.
A device that measures the current in a loop of the circuit that it is connected in series with. An ideal ammeter is modelled to have zero resistance.
Define current.
The rate of flow of charge in a circuit.
Define electromotive force.
The amount of energy transferred by a source to each unit of charge that passes through it.
Define internal resistance.
The resistance to the flow of charge within a source. Internal resistance results in energy being dissipated within the source.
Define light dependent resistor.
A light sensitive semiconductor whose resistance increase when light intensity decreases.
Define ohmic conductor.
A conductor for which the current flow is directly proportional to the potential difference across it, when under constant physical conditions.
Define Ohm’s Law.
The current and potential difference though an ohmic conductor held under constant physical conditions are directly proportional, with the constant of proportionality being resistance.
Define parallel circuits.
Components are said to be connected in parallel when they are connected across each other.
Define potential divider.
A method of splitting a potential difference, by connecting two resistors in series. The total potential difference is split in the ratio of their resistances.
Define resistance.
A measure of how difficult it is for current to flow through a material.
Define resistivity.
A quantity that is proportional to an object’s resistance and cross-sectional acres and inversely proportional to the object’s length.
Define superconductor.
A material which has zero resistivity when the temperature is decreased to, or below, the material’s critical temperature. Superconductors can be used to produce strong magnetic fields and recur energy loss when transmitting electric power.
Define terminal potential difference.
The potential difference crops the terminals of a power source. It is equal to the source’s emf minus any voltage drop over the source’s internal resistance.
Define thermistor.
A temperature sensitive semiconductor whose resistance increases when temperature decreases.
Define voltmeter.
A device used to measure the potential difference across components. An ideal voltmeter is modelled to have infinite resistance.
