Chapter 4: Q33E (page 950)
The magnetic field around the head has been measured to be approximately. Although the currents that cause this field are quite complicated, we can get a rough estimate of their size by modelling them as a single circular current loop 16 cm (the width of a typical head) in diameter. What is the current needed to produce such a field at the center of the loop?
Short Answer
The current needed to produce at the center of the loop is.