# How Current and Potential Difference (Pd) Are Related for a Fixed Resistance

How current and potential difference (pd) are related for a fixed resistance

You will need:

Method

1 Set up the circuit shown in the diagram.

2 Use a table to record values of the current through and potential difference (pd) across the resistor R as you gradually move the slider on the variable resistor from maximum to minimum resistance.

3 Draw a graph of potential difference (y-axis) against current (x-axis).

Conclusion

1 Look at the graph. What can you say about the relationship between current and potential difference? How do you know?

2 Work out the ratio pd/current for each pair of current and pd values in your table of results.

What do you notice?

3 Find the gradient of your graph. What do you notice?

How current and potential difference (pd) are related for a fixed resistance

You will need:

Method

1 Set up the circuit shown in the diagram.

2 Use a table to record values of the current through and potential difference (pd) across the resistor R as you gradually move the slider on the variable resistor from maximum to minimum resistance.

3 Draw a graph of potential difference (y-axis) against current (x-axis).

Conclusion

1 Look at the graph. What can you say about the relationship between current and potential difference? How do you know?

2 Work out the ratio pd/current for each pair of current and pd values in your table of results.

What do you notice?

3 Find the gradient of your graph. What do you notice?

How current and resistance are related for a fixed potential difference

You will need:

Conclusion

1 How does the current change as the length of wire increases?

2 Suggest how the resistance of the wire varies with the length in the circuit.

3 Decide how the current changes as the resistance of the wire increases.

4 What graph could you plot to test whether the current and resistance are inversely proportional?

5 Plot this graph to see whether this is true.

How current and resistance are related for a fixed potential difference

You will need:

Conclusion

1 How does the current change as the length of wire increases?

2 Suggest how the resistance of the wire varies with the length in the circuit.

3 Decide how the current changes as the resistance of the wire increases.

4 What graph could you plot to test whether the current and resistance are inversely proportional?

5 Plot this graph to see whether this is true.