A student was asked to investigate the variation of current with potential difference for a thin metallic conductor - Leaving Cert Physics - Question 4 - 2013

The device used to vary the potential difference across the conductor is the variable resistor (rheostat).

The student rotated the dial on the variable resistor, which altered the resistance in the circuit. This adjustment changes the potential difference available across the conductor, allowing the student to take measurements at different voltage levels.

To plot the graph:

1. Label the x-axis as 'Potential Difference (V)' and the y-axis as 'Current (A)'.
2. Mark the data points from the table: (1.0, 0.17), (2.0, 0.34), (3.0, 0.50), (4.0, 0.64), (5.0, 0.77), (6.0, 0.88).
3. Plot these points accurately on the graph paper.
4. Connect the points to reveal the trend, noting the linear relationship typically expected in Ohm's law.

Using Ohm's law, which states that: $V = I imes R$

• Find the corresponding potential difference (V) on the graph for I = 0.7 A. Let's say it is approximately 4.5 V (based on interpolation from the graph).
• Then calculate Resistance (R): $R = \frac{V}{I} = \frac{4.5 V}{0.7 A} = 6.43 \Omega$

Thus, the resistance of the conductor is approximately 6.4 Ω.

The graph will display a straight line passing through the origin, indicating a linear relationship between current and potential difference. This shape denotes that as the potential difference increases, the current also increases proportionately, which is characteristic of Ohm's law. The slope of the graph represents the resistance of the conductor, implying that resistance remains constant under typical operating conditions.