P2b

• This is an example of a series circuit (on the left) and a  parallel circuit (on the right).

• Current - the flow of electrons round the circuit. Current will not flow if there is no voltage across the component.
• Voltage - the driving force that pushes the current round.
• Resistance - anything in the circuit that slows the flow down.

If you increase the voltage - then more current will flow.

If you increase the resistance - then less current will flow (or more voltage would be needed to keep the same current).

• The Ammeter - measures the current (in amps) flowing throught the component.
• Must be put in a series circuit (see diagram card).
• The Voltmeter - measures the voltage (in volts) across the component.
• Must be put in a parallel circuit around the component under test.
• The proper name for voltage is 'Potential Difference'.

Resistance = Potential Difference / Current

• For straight line graphs - the resistance of the component is steady. The steeper the gradient the lower the resistance. 
• For curved graphs - the resistance is changing.