Electricity Flashcards
What is an ammeter?
A device that measures the current in the loop of the circuit that it is connected in series with. An ideal ammeter is modelled to have zero resistance.
What is current?
The rate of flow of charge in a circuit.
What is the electromotive force?
The amount of energy transferred by a source, to each unit of charge that passes through it.
What is internal resistance?
The resistance to the flow of charge within a source. Internal resistance results in energy being dissipated within the source.
What is an LDR?
A light sensitive semiconductor whose resistance increases when light intensity decreases.
What is an ohmic conductor?
A conductor for which the current flow is directly proportional to the potential difference across it, when under constant physical conditions.
What is Ohm’s law?
The current and potential difference through an ohmic conductor held under contestant physical conditions are directly proportional, with the constant of proportionality being resistance.
What are parallel circuits?
Components are said to be connected in parallel when they are connected across each other (separate loops).
What is a 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.
What is resistance?
A measure of how difficult it is for current to flow through a material.
What is resistivity?
A quantity that is proportional to an object’s resistance and cross-sectional area, and inversely proportional to the object’s length.
What are resistors in parallel?
The potential difference across resistors connected in parallel is identical for each resistor. The current is split between the resistors. The total resistance is equal to the inverse of the sum of the inverses of the resistances of the resistors.
What are resistors in series?
The current through resistors connected in series is identical for each resistor. The potential difference is split in the ratio of their resistances. The total resistance is equal to the sum of the resistances of the resistors.
What are series circuits?
Components are said to be connected in series when they are connected end to end (in one loop).
What is a 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 reduce energy loss when transmitting electric power.
