P2 Electricity
Current
Flow of electrical charge
Electrical flow will only flow in a complete circuit
Unit is ampere ‘A’
Potential difference (voltage) driving force that pushes the charge around ‘V’
Resistance is anything that slows the flow down
The current flowing through a component depends on the potential difference (voltage) across it
and the resistance of the component
Total charge
Q- charge, measured in C
I- Current, measured in A
T- time measured in seconds
Circuit Symbols
Resistance and V=IR
Voltage =
Current*Resistance
Investigating Resistance
Ammeter- measurers current in amps (should be places in series)
Voltmeter- measures potential difference (voltage)
1. Attach a crocodile clip to the wire level with 0 cm on the ruler
2. Attack the second crocodile clip (e.g.) 10 cm away
3. Close the switch, record the current through the wire and the voltage
4. Open the switch and move the second crocodile clip another 10cm down
5. Repeat this for a number of times
6. Use current and pd (voltage) to calculate the resistance
7. Plot a graph and you should get a straight line (resistance is directly proportional to length)
Current
Flow of electrical charge
Electrical flow will only flow in a complete circuit
Unit is ampere ‘A’
Potential difference (voltage) driving force that pushes the charge around ‘V’
Resistance is anything that slows the flow down
The current flowing through a component depends on the potential difference (voltage) across it
and the resistance of the component
Total charge
Q- charge, measured in C
I- Current, measured in A
T- time measured in seconds
Circuit Symbols
Resistance and V=IR
Voltage =
Current*Resistance
Investigating Resistance
Ammeter- measurers current in amps (should be places in series)
Voltmeter- measures potential difference (voltage)
1. Attach a crocodile clip to the wire level with 0 cm on the ruler
2. Attack the second crocodile clip (e.g.) 10 cm away
3. Close the switch, record the current through the wire and the voltage
4. Open the switch and move the second crocodile clip another 10cm down
5. Repeat this for a number of times
6. Use current and pd (voltage) to calculate the resistance
7. Plot a graph and you should get a straight line (resistance is directly proportional to length)
