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

Answer:

length is 23.228091 m

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