A long solenoid is formed by the winding 20 turns/cm. What will be the current necessary to produce a magnetic field of 20 millitesla inside the solenoid?
(μ₀/4π=10⁻⁷ tesla−meter/ampere)
a. 4.0 A
b. 1.0 A
c. 8.0 A
d. 2.0 A