Current electricity Flashcards
Potential difference
Work done per unit positive charge
PD equation
Volts = work done / charge (coloumbs)
Current
The rate of flow of charge
Current equation
Current (I) = Charge (C) / time (s)
Series circuit
One circuit / pathway and the current is the same everywhere in the circuit
Parallel circuit
Circuit has two or more pathways and the current splits, passing through the pathways before adding up again
Resistance
Material’s opposition to the flow of electric current
Calculating effective resistance - series
Add all resistance together (R1 + R2 etc…)
Calculating effective resistance - parallel
1/ R1 + 1/R2 etc…
Ohms law
The current through a conductor is directly proportional to the potential difference across the conductor at room temperature
Ohms law equation
Potential difference in Volts (V) = Current (I) x Resistance in ohms
Ohmic conductors
Conductors that obey Ohm’s law such as pure metal. On graph, the gradient of V vs I = resistance
Non-ohmic conductors
Conductors that do not obey Ohm’s law such as filament lamp bulbs. On a graph constant gradient = constant resistance, changing gradient = changing resistance
Series circuit potential difference
Potential difference divides between resistors. The voltmeter readings across series resistors add up the total pd across the battery
Parallel circuit potential difference
Potential difference is the same across all points in the parallel circuit. Voltmeter readings will all be the same
