Physics Homework: What current in the solenoid would be needed to produce a field of..

Q)
What current in the solenoid would be needed to produce a field of 1.5×10−3 T but in the opposite direction?

Sol:

From question 2, magnetic field of 1.6*10^-3, produces 2400 turns

Hence, magnetic field of 1.5*10^-3, produces 2250 turns

Magnetic field, B=u_o*n*I

Current, I = 1.5*10^-3/(4*pi*10^-7*2250)= 0.53A