# Physics Required Practical: Resistance

Includes;

- The Method (In Blue)

- Common Mistakes (In Yellow)

- Safety Notes (In Pink)

• Created by: Hannah
• Created on: 19-03-19 17:23
• Physics Required Practical: Resistance
• Method 1: How the length of a wire affects resistance...
• 1. Set up a series circuit with a power pack, ammeter, voltmeter and a resistor (the component that you're testing).
• 2. Attach your component, a metre rule with a wire, where the resistor symbol is. Use crocodile clips to add this component in to your circuit.
• 3. Place the crocodile clips so that they are 100cm apart. Turn on the power pack at 4 V. Measure and record both the potential difference and current of the wire.
• 4. Turn off the power pack. Reduce the length of the wire between the crocodile clips by 10cm.
• 5. Repeat steps 4 and 5 for all wire lengths down to 10cm. Turn off the power pack if the wire starts glowing or smoking.
• 6. Calculate the resistance for each length of the wire, using the formula: resistance = potential difference / current.
• 7. Plot a graph of resistance against length of wire.
• Method 2: Investigating resistors in series and parallel circuits...
• 1. Set up the same circuit as the previous method, but with two resistors in series.
• 2. Turn on the power pack at 4 V. Measure and record the potential difference across the power pack. Then measure and record the potential difference across each individual resistor and the current through them.
• 3. Calculate the total resistance of the circuit with resistors in series.
• 4. Set up the circuit for two resistors in parallel. Repeat steps 2 - 4 for the resistors in parallel. Then calculate the total resistance of the circuit for resistors in parallel, and compare the results.
• If your readings keep fluctuating, try to get an average value. Ammeters and voltmeters rarely stay at an exact value.
• Short lengths of wire are likely to get hot. Use low values of potential difference. Switch off between readings.
• You can add a bulb to your circuit to stop the wire from getting too hot.