Investigating Resistance

First, you’ll need to find at least four identical resistors
Then build the circuit shown on the right using one of the resistors. Make a note of the potential difference of the battery
Measure the current through the circuit using the ammeter. Use this to calculate the resistance of the circuit using R=V/I
Add another resistor, in series with the first
Again, measure the current through the circuit and use this and the potential difference of the battery to calculate the overall resistance of the circuit
Repeat steps 4 and 5 until you’ve added all of your resistors
Plot a graph of the number of resistors against the total resistance of the circuit

Using the same equipment as before, build the same initial circuit
Measure the total current through the circuit and calculate the resistance of the circuit using R=V/I
Next, add another resistor, in parallel with the first
Measure the total current through the circuit and use this and the potential difference of the battery to calculate the overall resistance of the circuit
Repeat steps 3 and 4 until you’ve added all of your resistors
Plot a graph of the number of resistors in the circuit against the total resistance

You should find that adding resistors in series increases the total resistance of the circuit
The more resistors you add, the larger the resistance of the whole circuit
When you add resistors in parallel, the total current through the circuit increases-so the total resistance of the circuit has decreased
The more resistors you add, the smaller the overall resistance becomes
These results agree with what you’ve learnt about resistance in series and parallel circuits.