Question

ichrome wire of cross-sectional radius 0.791 mm is to be used in winding a heating coil. If the coil must carry a current of 9.25 A when a voltage of 1.20 3 102 V is applied across its ends, find (a) the required resistance of the coil and (b) the length of wire you must use to wind the coil.

Answer 1

length is 23.228091 m

Step-by-step explanation:

Given data

radius = 0.791 mm = 0.791 ×
`10^(-3)` m

current = 9.25 A

voltage = 1.20 × 10² V

to find out

resistance and length of wire

solution

we know the resistance formula that is

resistance = voltage / current

resistance = 1.20 × 10² /9.25

resistance = 12.97

so resistance is 12.97 ohm

and length of nichrome wire formula is

length = resistance × area / specific resistance of wire

so specific resistance of wire we know = 1.1 ×
`10^(-6)`

and area =
`\pi` × r² =
`\pi` × (0.0791×
`10^(-3)`)²

area = 1.97 ×
`10^(-6)`

length = 12.97 × 1.97 ×
`10^(-6)` / 1.1 ×
`10^(-6)`

so length is 23.228091 m