1.1. A student is determining the resistance of a piece of wire.

    Fig. 2.1 shows the circuit she uses.

Record the current $I$ in the circuit, as shown on the ammeter in Fig. 2.2.

$I$ = ........................................................ 

1.2. The student places the sliding contact C at a distance $l$ = 20.0 cm from P. The voltmeter reading is shown in Fig. 2.3. Record the voltmeter reading in Table 2.1 for $l$ = 20.0 cm.

Table 2.1

1.3. The student repeats the procedure using values of $l$ = 40.0 cm, 60.0 cm, 80.0 cm and 100.0 cm. The readings are shown in Table 2.1.

Complete the column headings in the table.

Table 2.1

1.4. Plot a graph of V / V (y-axis) against $l$ / cm (x-axis). Start both axes at the origin (0, 0).

1.5. Extended tier only

(i) Determine the gradient G of the graph. Show clearly on the graph how you obtained the necessary information.

G = ........................................................ [2]

(ii) Calculate the resistance R of each centimetre of the wire. Use the following equation:

$R=\frac{Gk}{I}$,

where k = 1.0 V/cm and where $I$ is the current recorded in (a).

  Include the unit.

R = ........................................................ [2]