State four additional items of electrical laboratory equipment required to acquire data to plot these electrical profiles (excluding the four circuit elements and standard connection leads).

During testing, the engineer must ensure that the constantan wires are maintained at a constant ambient temperature.

Explain why maintaining a constant temperature is critical to the validity of the results.

Outline two practical laboratory techniques that can be used to prevent or minimise temperature fluctuations in the wires during the data collection process.

Four different current–voltage ($I$–$V$) profiles are described below. Match each component to its corresponding graph description:

• Graph A: A linear relationship passing through the origin, exhibiting a very high rate of change of current with respect to potential difference.
• Graph B: A linear relationship passing through the origin, exhibiting a low rate of change of current with respect to potential difference.
• Graph C: A symmetrical curve passing through the origin whose gradient continuously decreases as the magnitude of the applied voltage increases in either direction.
• Graph D: A curve showing negligible conduction under reverse bias and low forward bias, but an abrupt, massive surge in current once a specific forward potential difference is reached.