When the starter motor on a car is engaged, there is a 310 A current in the wires between the battery and the motor. Suppose the wires are made of copper and have a total length of 1.0 m.

What minimum diameter can the wires have if the voltage drop along the wires is to be less than 0.55 V? (answer in mm)

Relax

Respuesta :

Answer:

Diameter will be 351.42 mm

Explanation:

We have given current flowing in the copper wire i = 310 A

Voltage drop across the wire V = 0.55 volt

We know that resistance is given by [tex]R=\frac{V}{i}=\frac{0.55}{310}=0.00177\Omega[/tex]

Length of the copper wire l = 1 m

Resisitivity of the copper wire [tex]\rho =1.72\times 10^{-8}\Omega m[/tex]

We know that resistance [tex]R=\frac{\rho l}{A}[/tex]

[tex]0.00177=\frac{1.72\times 10^{-8}\times  1}{A}[/tex]

[tex]A=969.4545\times 10^{-8}m^2[/tex]

As area [tex]A=\pi r^2[/tex]

[tex]3.14\times r^2=969.4545\times 10^{-8}[/tex]

[tex]r=17.57\times 10^{-4}m[/tex]

So diameter [tex]d=17.57\times 10^{-4}\times 2=35.142\times \times 10^{-4}m[/tex] = 351.42 mm