posted by opp .
Two concentric circular wire loops in the same plane each carry a current. The larger loop has a current of 8.62 A circulating clockwise and has a radius of 6.09 cm. The smaller loop has a radius of 4.42 cm. What is the current in the smaller loop if the total magnetic field at the center of the system is zero?
μ₀•I1/2•R = μ₀•I2/2•r
I2=I1•r/R=8.62•4.42/6.09 = 6.26 A (anticlockwise)