Electricity Flashcards
What is Electrical Current?
The rate of flow of positive charge carriers. It is measured in units of amperes (A) or amps
The direction of conventional current?
Positive to negative
The direction of flow of electrons?
Negative to positive
What is potential difference?
The work done per unit charge flowing between two points and is measured in units of volts (V).
What is Resistance?
A measure of how difficult it is for current to flow through a material.(The ratio of the potential difference to the current)
Ohm’s law states
For a conductor at a constant temperature, the current through it is proportional to the potential difference across it
For an ohmic conductor, the I–V graph is:
a straight line through the origin
For a semiconductor diode, the I–V graph is:
a horizontal line that goes sharply upwards
For a filament lamp, the I–V graph:
has an ‘S’ shaped curve
What is forward bias?
When the current is in the direction of the arrowhead symbol
Superconductor
A material in which there is no resistance past the critical temperature
Kirchhoff’s First Law
The sum of the currents entering a junction always equal the sum of the currents out of the junction.
Kirchhoff’s Second Law
The total e.m.f. in a closed circuit equals the sum of the potential differences across each component
electromotive force (e.m.f)
The amount of chemical energy converted into electrical energy per coulomb of charge when passing through a power supply.
