Electricity Flashcards
Current
The rate of flow of charge in a circuit.
Electromotive Force (EMF) (ε)
The amount of energy transferred by a source, to each unit
of charge that passes through it
ε = I (R + r)
Internal Resistance
The resistance to the flow of charge within a source. Internal
resistance results in energy being dissipated within the source
Ohm’s Law
The current and potential difference through an ohmic conductor held under constant physical conditions are directly proportional, with the constant of proportionality being resistance.
V = IR
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.
Resistivity
A quantity that is proportional to an object’s resistance and
cross-sectional area, and inversely proportional to the object’s length.
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
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.
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
Terminal Potential Difference
The potential difference across the terminals of a power source. It is equal to the source’s emf minus any voltage drop over the source’s internal resistance.
