P4 - Electric Circuits (PAPER 1) Flashcards
What is the difference between a battery and a cell
a battery is two or more cells connected together
What determines the size of an electric current
The rate of flow of charge
What is the formula for the rate of flow of charge
charge flow (coulombs) = current(Amps) x time taken(s)
What is an ammeter used to measure
electric current
What is a voltmeter used to measure
potential difference (voltage)
What does a fuse do
It breaks the circuit if the current going through it is greater than a certain amount
What does a diode do
It only allows the current to pass through in one direction
what is potential difference
work done on the bulb by each coulomb of charge that passes through it
What is resistance
opposition to the flow of the current
What is Ohm’s law
it states that ‘the current through a resistor at constant temperature is directly proportional to the potential difference across the resistor
what happens when the potential difference across a resistor is reversed
the charge through it reverses
what happens to the resistance of a bulb filament as its temperature increases
The resistance increases
what is the equation of the resistance of an appliance
resistance (Ω) = potential difference (V) / current (A)
what happens to the resistance of a temperature dependent resistor (thermistor) as its temperature increases
the resistance decreases
what happens to the resistance of a light dependent resistor (LDR) as the light level increases
the resistance decreases
