Opening the switch in the circuit is essential after taking each reading to prevent the wire from heating up.
How to explain
When current flows through a wire, it generates heat due to resistance. Continuously passing current without breaks can cause the wire's temperature to rise, altering its resistance and potentially affecting the accuracy of subsequent readings.
By opening the switch, the circuit is broken, stopping the current flow, allowing the wire to cool down, ensuring more accurate and consistent resistance measurements.
Complete Question:
In an experiment measuring the resistance of a wire using a circuit with an ammeter and a voltmeter, why should the student open the switch after taking each reading?