Note the potential difference $V_1$ and the current $I_1$ shown in Fig. 2.2 and Fig. 2.3.
Calculate the effective resistance $R_1$ of the resistor combination using the equation $R_1 = \frac{V_1}{I_1}$.
Suggest why the switch is opened after the readings of potential difference and current have been taken.
Calculate the effective resistance $R_2$ of the resistor combination using the equation $R_2 = \frac{V_2}{I_2}$. Write down the value of $2R_2$.
State whether the results show that the resistors are identical. Support your statement with a calculation.
Suggest one observation that the student makes while carrying out the experiment that supports the idea that filament lamps change resistance because of heating.
Complete the circuit diagram in Fig. 2.5 to show a third way of linking three lamps between X and Y.