Series Circuits

• In series circuits, the different components are connected in a line, end to end, between the +ve and -ve of the power supply (except for voltmeters, which are always connected in parallel, but they don't count as part of the circuit)
• If you remove or disconnect one component, the circuit is broken and they all stop. This is generally not very handy, and in practice very few things are connected in series
• Potential difference is shared
• In series circuits the total pd of the supply is shared between the various components. So the potential differences round a series circuit always add up to equal the source pd: V(total) = V1 + V2 + ...
• Current is the same everywhere
• In series circuits the same current flows through all components: I1 = I2 = ...
• The size of the current is determined by the total pd of the cells and the total resistance of the circuit: I=V/R
• Resistance adds up
• In series circuits the total resistance of 2 components is just the sum of their resistances: R(total) = R1 + R2
• Resistance is added up because by adding a resistor in series, the 2 resistors have to share the total pd
• The potential difference across each resistor is lower, so the current through each resistor is also lower
• In a series circuit, the current is the same everywhere so the total current in the circuit is reduced when a resistor is added. This means the total resistance of the circuit increases
• The bigger a component's resistance, the bigger its share of the total potential difference
• Cell potential differences add up
• There is a bigger pd when more cells are in series, if they're all connected the same way
• When 2 cells with a potential difference of 1.5V are connected in series they supply 3 V between them