Problem 10P

An iron rod of length L and square cross section (side a) is given a uniform longitudinal magnetization M, and then bent around into a circle with a narrow gap (width w), as shown in Fig. 6.14. Find the magnetic field at the center of the gap, assuming w ≫ a≫ L. [Hint: treat it as the superposition of a complete torus plus a square loop with reversed current.]

Solution 10P

Step 1 of 3:

Consider an iron rod of length and square cross section is given a uniform longitudinal magnetization M, and then bent around into a circle with a narrow gap having width .

We need to find out the magnetic field at the center of the gap assuming .