A solenoid is wound with N476 turns on a form D22 cm in diam

A solenoid is wound with N=476 turns on a form D=2.2 cm in diameter and L=87 cm long. The windings carry a current in the sense that is shown. The current produces a magnetic field, of magnitude 7.5 mT, at the center of the solenoid. What is the value of the current in the solenoid windings? Express the answer with two decimal places. ( µ₀ = 1.26×10^-6 T·m/A).

Solution

I = B L / mu₀ N

= (7.5 * 10^-3 * 87 * 10^-2) / (4 pi * 10^-7 * 476)

I = 10.91 A