State one feature of the wire that must stay unchanged if the comparison is to be fair.
On Fig. 1.1, draw a voltmeter symbol so that it measures the voltage across the wire length.
Name the apparatus used to measure the wire length between the crocodile clips.
Record the current and voltage readings for this wire length. current = [BLANK] mA voltage = [BLANK] V
On Fig. 1.3, plot the graph of $R/\Omega$ on the $y$-axis against $l$/cm on the $x$-axis. Start both axes from the origin $(0,0)$. Draw the straight line of best fit.
State the relationship between $R$ and $l$ shown by your graph.
Use your graph to determine the length of wire that has a resistance of $14\,\Omega$. Show how you determine this value on your graph. length of wire needed = [BLANK] cm
A second student does the same experiment. He uses one continuous $120.0\,\text{cm}$ length of wire. He places two crocodile clips at different positions along the $120.0\,\text{cm}$ wire so that the required length of wire for each measurement lies between them for every reading. He switches off the power supply after each reading and leaves a short pause before taking the next reading. Suggest a reason for waiting a short time.