Question
To see why an MRI utilizes iron to increase the magnetic field created by a coil, calculate the current needed in a 400-loop-per-meter circular coil 0.660 m in radius to create a 1.20-T field (typical of an MRI instrument) at its center with no iron present. The magnetic field of a proton is approximately like that of a circular current loop $0.650 \times 10^{-15} \textrm{ m}$ in radius carrying $1.05 \times 10^4 \textrm{ A}$. What is the field at the center of such a loop?

$2390 \textrm{ A}$

$1.01 \times 10^{13} \textrm{T}$

Solution Video