Consider two current-carrying circular loops. Both are made from one strand of wire and both carry the same current, but one has twice the radius of the other. Compared to the magnetic field at the center of the smaller loop, the magnetic field at the center of the larger loop is

Question

Quizplus · Accepted Answer

The magnetic field at the center of a current-carrying loop is given by $B = \frac{\mu_0 I}{2R}$, where $I$ is the current and $R$ is the radius of the loop. If one loop has twice the radius of the other, but both carry the same current, the magnetic field at the center of the larger loop will be half that of the smaller loop, not 2, 4, or 8 times stronger.

Consider Two Current-Carrying Circular Loops