Enter the values of $V$ and $I$ into Table 1.1.
Complete the top row of Table 1.1 by calculating the resistance $R$ of the lamp when $l = 10.0\,\text{cm}$. Use the equation shown. $R = \frac{V}{I}$
The student leaves out the current value for $l = 100.0\,\text{cm}$. Calculate the current and enter it in Table 1.1.
The student looks at Table 1.1 and says that the resistance $R$ of the lamp is directly proportional to the length $l$. State whether you agree with the student’s claim. Support your answer with values taken from Table 1.1.
On the grid in Fig. 1.3, draw a graph of $R$ on the $y$-axis against $V$ on the $x$-axis. Begin both axes at the origin $(0,0)$. Add a smooth curve of best fit.
Using your graph, describe how the resistance $R$ of the lamp varies as the potential difference $V$ across it changes.
Another student changes the circuit shown in Fig. 1.1. She uses a variable resistor to vary the current and potential difference instead of the resistance wire and the crocodile clip. Complete the circuit diagram in Fig. 1.4 to show this arrangement.