QUESTION 9 (Start on a new page.) The circuit diagram below was used to investigate the relationship between the current passing through resistor R and the potential difference across it at constant temperature - NSC Technical Sciences - Question 9 - 2023 - Paper 1

The dependent variable in this investigation is the current, measured in amperes (A), as it responds to changes in the potential difference.

The shape of graph A shows a linear relationship between current and potential difference, indicating that resistor R follows Ohm's law, where current is directly proportional to the voltage. Graph B, however, shows a non-linear relationship, suggesting that the resistance is higher compared to that of graph A.

To find the power dissipated by resistor R, we use the formula:

$P = I^2 R$

From graph A, at the current of 0.6 A, the corresponding voltage can be taken as 1.5 V. First, we can find the resistance using Ohm's law:

$R = \frac{V}{I} = \frac{1.5 \, V}{0.6 \, A} = 2.5 \, \Omega$

Now we can calculate the power:

$P = (0.6 \, A)^2 \times 2.5 \, \Omega = 0.36 \, A^2 \times 2.5 \, \Omega = 0.9 \, W$

The resistance of graph A is LOWER THAN the resistance of graph B, as indicated by the steeper slope of graph A compared to graph B.

The reason graph A has a lower resistance than graph B is due to the different slopes of their respective graphs. The slope of a current versus potential difference graph represents resistance. Since graph A has a steeper slope, it indicates a lower resistance, whereas the flatter slope of graph B shows a higher resistance. Therefore, for the same current, the potential difference in graph B is higher than in graph A.