Define the following terms as used in magnetism: (i) reluctance; (ii) hysteresis. (5 marks)craft1 electrical June/July 2020

(i) Reluctance is a measure of the resistance of a material to being magnetized. It is defined as the ratio of the magnetomotive force (MMF) required to produce a certain level of magnetization in the material to the resulting magnetization. The unit of reluctance is the ampere-turn per weber (At/Wb).

(ii) Hysteresis is the lag in the response of a material to changes in an applied magnetic field. It is typically observed as a loop on a graph of magnetization versus applied magnetic field, and it is a measure of the energy loss associated with reversing the magnetization of the material. In a material with hysteresis, it takes more energy to magnetize the material in one direction than it does to demagnetize it, and vice versa. This phenomenon is important in the design of devices such as transformers and motors, as it can result in losses due to the hysteresis loop.