Question

Nichrome wire of cross-sectional radius 0.796 mm is to be used in winding a heating coil. If the coil must carry a current of 9.75 A when a voltage of 1.50 ✕ 102 V is applied across its ends, find the following. (a) the required resistance of the coil Ω (b) the length of wire you must use to wind the coil m

Answer 1

Given,

Voltage across the Nichrome wire is 1.50 X 102 = 150 volt,

Current in the wire (I) = 9.75 A

Radius of the wire = 0.796 mm = 0.796 X 10-3 m

Cross section area of the wire:

(a)

The required resistance of the coil is

(b)

The resistance of a wire is given by

Where is resistivity of the wire.

For Nichrome wire,

Putting all the values in the resistance equation, we get