A piece of copper wire of resistance 5 Ω at 25 °C is connected across a 12 V battery.
PHYSICS · Multi-part · CBSE · Physics · Current Electricity · Current Electricity
Problem
A piece of copper wire of resistance 5 Ω at 25 °C is connected across a 12 V battery.
(i) Calculate the current through the wire immediately after the circuit is switched on, when the wire is still at 25 °C.
(ii) After some time the wire heats up and its resistance becomes 8 Ω while the applied voltage remains 12 V. Calculate the current now.
(iii) Find the percentage decrease in current due to heating of the wire.
(iv) Explain in two to three sentences why the current decreases even though the potential difference is unchanged.