Unit 2 electricity Flashcards
(27 cards)
What is the formula for charge flow
Charge flow = current x time
What is the formula for potential difference
Potential difference = current x resistance
What is the formula for total resistance
Total resistance = resistance of component 1 + resistance of component 2
What is the formula for power
Power = (current)2 x resistance
What is the equation for energy transfered
Power x time
What is the other equation for energy transferred
Energy transfered = Charge flow x potential distance
Definition of electrical current
Rate of flow of charge
Difference between series and parallel circuit
Series: only one path for current to flow; Parallel: more than one path/has branches
What happens to resistance of a filament lamp as it heats up?
higher temperature increases the resistance
What happens to resistance of a thermistor as temperature increases?
It decreases (in a non-linear way)
What happens to resistance of a LDR as light intensity increases?
It decreases (in a non-linear way)
What is “special” about a diode?
Current can only flow through it in one direction
What happens to current in a series circuit?
Same in all parts of the circuit
What happens to current in a parallel circuit?
Current into a junction equals current out of the junction
What happens to potential difference in a series circuit?
It is shared between the components
What happens to potential difference in a parallel circuit?
It is the same in all branches of the circuit (also the same as the power supply)
Equipment used to measure current
Ammeter
Equipment used to measure potential difference
voltmeter
How should an ammeter be connected in a circuit?
In series with the component
How should a voltmeter be connected in a circuit?
In parallel with the component
Which component is used to vary the current in a circuit?
Variable resistor
When measuring resistance of a wire, why should the circuit only be turned on for a short period of time?
Stop the wire heating up
Direction of conventional current
positive to negative
What carries the charge in a wire?
electrons
