The starter motor of a car engine draws a current of 150 A f

The starter motor of a car engine draws a current of 150. A from the battery. The copper wire to the motor is 4.40 mm in diameter and 1.3 m long. The starter motor runs for 0.8840 m until the car engine starts

Solution

I = 150 A

d = 4.4 mm

L = 1.2 m

t = 0.84 s

a)

charge passing = I*t

= 150*0.84

= 126 C

b)

Current , I = n*e*A*v

where n = free electron density of copper = 8.47*10^28

e = 1.6*10^-19 C

A = pi*d^2/4 = pi*(4.4*10^-3)^2/4 = 1.52*10^-5 m2

v = drift velocity

So, 150 = 8.47*10^28*1.6*10^-19*1.52*10^-5*v

So, v = 7.3*10^-4 m/s

So, distance moved = v*t = 7.3*10^-4*0.84 = 6.13*10^-4 m <-------answer