Question

Current flowing in conductors a and b is same. What is the ratio of the magnetic field produced around the conductor a at a distance of 5cm from the conductor to the magnetic field produced around the conductor b at a distance of 2cm from this conductor?

Answer 1

$B_a=\mu\mu_0\frac{I}{2\pi a}$

$B_b=\mu\mu_0\frac{I}{2\pi b}$

$B_a/B_b=b/a=2/5=0.4$