If the radius of the coils r=10.5cm, there are n=540 windings in both coils, and the current flowing in the wire is 5.7 A, what is the magnitude of the magnetic field at the center?
a) 1.23×10⁻³T
b) 2.46×10⁻³T
c) 3.69×10⁻³T
d) 4.92×10⁻³T