Current of Electricity Flashcards
Define electric current
Electric current is the rate of flow of electric charge
What is formula relating current and charge?
I = Q/t (1 A = 1C/s
Define conventional current
The flow of positive charges from the positive to the negative terminal
Define electron flow
Flow of electrons from negative to positive terminal
Define electromotive force
The work done by a source in driving a unit charge around a complete circuit.
What is the formula relating e.m.f. and work done
E = W/Q (1V = 1 J/C)
Define potential difference
The work done to drive a unit charge through a component
What is e.m.f. of a circuit when a switch in the circuit is off?
The e.m.f. provided by the battery
What is potential difference of a component when a switch in the circuit is off?
0V
Define resistance
Resistance of a component is the ratio of the potential difference V across it to the current I flowing through it.
Why does increased length of wire increase resistance of wire?
The longer the wire, the more collisions the electrons will make with the metal particles of the wire, the higher the resistance
Why does increased cross-sectional area of wire decrease resistance?
The larger the cross-sectional area of the wire, the greater the number of electrons that can flow through it, the lower the resistance
What is an application of nichrome?
Heating coils of electric kettles
Formula for resistance of a wire
R = p(l/A)
What is Ohm’s Law?
Ohm’s law states that current passing through a metallic conductor is directly proportional to the potential difference across it, provided physical conditions such as temperature remain constant
