The magnetic field of the brain has been measured to be approximately 2.5×10⁻¹² T. Although the What current is needed to produce such a field at the center of the loop? currents that cause this field are quite complicated, we can get a rough estimate of their sizeby modeling them as a single circular current loop 16 cm (the width of a typical head) in diameter. What current is needed to produce such a field at the center of the loop?