Simple and approximate expressions of demagnetizing factors of uniformly magnetized rectangular rod and cylinder

Demagnetizing factors of the rectangular rod and cylinder magnetized uniformly along the long axis are found to be expressed by the simple and approximate expressions 1/(2n+1) and 1/[2(2n/(π)1/2) +1], respectively, where n is the dimensional ratio. The error which is the difference of the value evaluated by 1/(2n+1) from the value evaluated by the exact expression of the demagnetizing factor is less than 5.48% for the rectangular rod with n<70. The error of the value evaluated by the expression 1/[2(2n/(π)1/2) +1] for the cylinder is also found to be less than 4.25% for n<100.