Physics 9702/33 — May/June 2021

You have been provided with two identical wooden strips labelled A and B.

Measure and record the length $L$ of the wire between the nails on strip A, as shown in Fig. 1.1.

$L$ = ______

Set up the circuit shown in Fig. 1.2.

• $F$, $G$, $H$ and $J$ are crocodile clips.
• Attach $G$ to the wire on wooden strip A so that the distance $x$ between the nail on strip A and $G$ is approximately $30\text{ cm}$, as shown in Fig. 1.2.
• Attach $H$ to the wire on wooden strip B so that it is the same distance $x$ from the nail on strip B.
• Close the switch.
• Record $x$ and the ammeter reading $I$.
• Open the switch.

$x$ = ______
$I$ = ______

Vary $x$ and repeat (b) until you have six sets of readings of $x$ and $I$. Include your values from (b).

Record your results in a table. Include values of $\frac{1}{I}$ in your table.

It is suggested that the quantities $I$ and $x$ are related by the equation

where $P$ and $Q$ are constants.

Using your answers in (d)(iii), determine values for $P$ and $Q$. Give appropriate units.

$P$ = ______
$Q$ = ______

Theory suggests that

where $\rho_A$ is the resistivity of the wire on strip A and $\rho_B$ is the resistivity of the wire on strip B.

Calculate $\frac{\rho_A}{\rho_B}$.

$\frac{\rho_A}{\rho_B}$ = ______