A heater coil is

(a) Let R be the resistance of the coil.

Given, resistivity, ρ = 1.0 × 10^–8 Ω m

The power P consumed by a coil of resistance R when connected across a supply V is given by Joule’s heating effect-

(b) We know resistance R is given by-

where

ρ = resistivity of the material

l = length of the wire

A= area of cross section of the wire

Given, cross-sectional area of the wire is 0.5 mm²

(c) Let n be the number of turns in the given coil.

Given, radius of each turn is 4.0 mm

Then,

Where,

l = length of the coil

r=radius of the coil