Amotorcyclist is making an electric vest that, when connected to the motorcycle's 12 v battery, will warm her on cold rides. she is using 0.22-mm-diameter copper wire, and she wants a current of 3.9 a in the wire.
what length wire must she use?

Length of the wire, l = 6.78 meters

Explanation:

It is given that,

Voltage of the motorcycle, V = 12 V

Diameter of the copper wire, d = 0.22 mm

Radius, r = 0.11 mm = 0.00011 m

Current in the wire, I = 3.9 A

Resistivity of the copper wire,

The resistance of wire is calculated using Ohm's law as :

R = 3.07 ohms

Resistance of wire in terms of length is given by :

l = 6.78 meters

So, the length of the wire is 6.78 meters. Hence, this is the required solution.

answer and explanation;