A room-heater is designed to operate on mains and draw a steady current of

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

Problem

A room-heater is designed to operate on

230\,\text{V}

mains and draw a steady current of

5.0\,\text{A}

. The heating element is to be made from wire of length

20\,\text{m}

. (i) Calculate the resistance that the heating element must possess when it is at its normal operating temperature. (ii) The manufacturer has stock wires of the following materials, each available in many diameters: Nichrome:

1.1\times10^{-6}\;\Omega\,\text{m}

Manganin:

4.2\times10^{-7}\;\Omega\,\text{m}

Copper:

1.7\times10^{-8}\;\Omega\,\text{m}

For each material, determine the cross-sectional area required to obtain the resistance calculated in part (i). (iii) Identify the most appropriate material for the heater coil from the list above and justify your selection on the basis of both the numerical result in part (ii) and the practical properties expected of a heating element.

Related theory

Browse the problem library