An electric heater element is to be made from nichrome wire.

PHYSICS · Multi-part · CBSE · Physics · Current Electricity · Current Electricity

Problem

An electric heater element is to be made from nichrome wire. (i) Determine the length of nichrome wire required to obtain a resistance of

20\,\Omega

if the wire has a diameter of

0.40\,\text{mm}

and the resistivity of nichrome is

1.1 \times 10^{-6}\,\Omega\,\text{m}

. (ii) If the same length of wire were instead made from copper of diameter

0.40\,\text{mm}

(resistivity

1.7 \times 10^{-8}\,\Omega\,\text{m}

), calculate its resistance. (iii) Despite copper having a much lower resistivity, explain why nichrome is preferred for heater elements.