A nichrome heating coil has a resistance of at

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

Problem

A nichrome heating coil has a resistance of

12\,\Omega

20^{\circ}\text{C}

. When a steady current of

3.0\,\text{A}

passes through it, its temperature rises to

120^{\circ}\text{C}

. For nichrome, assume that the resistance increases by

0.40\%

for every

1^{\circ}\text{C}

rise in temperature. Using these data, answer the following: (i) Calculate the resistance of the coil at

120^{\circ}\text{C}

. (ii) Determine the electrical power developed in the coil at

20^{\circ}\text{C}

. (iii) Determine the electrical power developed in the coil at

120^{\circ}\text{C}

. (iv) Find the percentage increase in power when the coil reaches

120^{\circ}\text{C}

compared with its value at

20^{\circ}\text{C}