A nichrome wire is tested for its electrical behaviour at two different temperatures

PHYSICS · Multi-part · A Level · Physics · Electricity · Electricity

Problem

A nichrome wire is tested for its electrical behaviour at two different temperatures. The potential difference

V

across the wire and the current

I

through it are measured as follows: (i) Using the data at

25\,^{\circ}\!\text{C}

, calculate the resistance of the wire for each reading and find the average value.

25\,^{\circ}\!\text{C}

data:

(V, I)

= (1.0 V, 0.10 A), (2.0 V, 0.20 A), (3.0 V, 0.30 A). (ii) Repeat the calculations for the data at

200\,^{\circ}\!\text{C}

and obtain the average resistance.

200\,^{\circ}\!\text{C}

data:

(V, I)

= (1.0 V, 0.06 A), (2.0 V, 0.11 A), (3.0 V, 0.15 A). (iii) Comment on whether the wire obeys Ohm’s law at each temperature, giving clear justification based on your calculations. (iv) Explain why a rise in temperature causes the observed change in the

V

–

I

behaviour of the wire.

Related theory

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