JJO AQA Electricity 1 Flashcards
What is current?
The flow of electric charge
or
How many electric charges pass a point every second
What is potential difference?
How much energy EACH electric charge picks up or drops off at a component.
What piece of equipment is used to measure current?
An ammeter
What piece of equipment is used to measure potential difference?
A voltmeter
What is the unit for current?
Amps (Amperes)
What is the unit for potential differences?
Volts
What is the unit for resistance?
Ohms
What causes resistance?
Metal ions: Electric charge bumps into metal ions as it moves through components.
Charge flow (C) =
Current (A) x time (s)
What is the unit for charge flow?
Coulombs
What happens to the current in a circuit if you add more lamps in series?
Explain your answer.
It decreases
Because there is more resistance: The electric charge bumps into more metal ions slowing it down.
What would happen to the current in a circuit if you increased the number of cells?
Explain your answer.
It would increase
Because each electric charge would be given more energy and therefore move faster.
Potential difference (V) =
Current (A) x resistance (ohms)
What happens to the resistance of a thermistor when temperature increases.
It decreases.
What happens to the resistance of an LDR when light intensity increases?
It decreases.
Give an example of a device that uses a thermistor.
A thermostat.
What is the potential difference of the UK electrical supply?
230V
What colour is the live wire in a plug?
Brown
What colour is the neutral wire in a plug?
Blue
What colour is the earth wire in a plug?
green and yellow
What does the live wire do?
Carries the potential difference
What does the neutral wire do?
Completes the circuit
What does the earth wire do and how does it work?
It stops the appliance becoming live and giving you an electric shock.
If the live wire touches the metal casing of the appliance the earth wire carries the potential difference away.
