Hawkins Electrical Guide v. 01 (of 10) / Questions, Answers, & Illustrations, A progressive course of study for engineers, electricians, students and those desiring to acquire a working knowledge of electricity and its applications

by N. Hawkins

That is,

magnetic flux = magnetomotive force / reluctance

expressed in units, the equation becomes:

maxwells = gilberts / oersteds

The gilbert is the unit of magnetomotive force, equivalent to the magnetomotive force of .7958 ampere turn.

It should be noted that in the electric circuit resistance causes heat to be generated and therefore energy to be wasted, but in the magnetic circuit reluctance does not involve any similar waste of energy.

Ques. Upon what does the reluctance of a magnetic circuit depend?

Ans. The reluctance is directly proportional to the length of the circuit, and inversely proportional to its cross sectional area.

The reluctance of a magnetic circuit is calculated according to the following equation:

reluctance = length in centimetres / (permeability × cross section in square centimetres)