Question

The concentric circles representing the magnetic field around a current carrying straight wire become larger and larger as we move away from the wire. How does magnetic field change on these concentric circles?

Answer 1

The magnetic field on those concentric circles decreases in strength as you move away from the wire it is inversely proportional to the distance r from the wire:

`B = μ_0 I/(2πr)`

The field at each circle is tangent to the circle (i.e., circumferential around the wire).