Electromagnetism Chapter 5 Learning Outcomes This chapter concerns the principles and laws governing electromagnetic induction and the concepts of self and mutual inductance. On completion of this chapter you should be able to use these principles to: 1 Understand the basic operating principles of motors and generators. 2 Carry out simple calculations involving the generation of voltage, and the production of force and torque. 3 Appreciate the signiﬁ cance of eddy current loss. 4 Determine the value of inductors, and apply the concepts of self and mutual inductance to the operating principles of transformers. 5 Calculate the energy stored in a magnetic ﬁ eld. 6 Explain the principle of the moving coil meter, and carry out simple calculations for the instrument.7 Describe the operation of a wattmeter and simple ohmmeter. 141 5.1 Faraday ’ s Law of Electromagnetic Induction It is mainly due to the pioneering work of Michael Faraday, in the nineteenth century, that the modern technological world exists as we know it. Without the development of the generation of electrical power, such advances would have been impossible. Thus, although the concepts involved with electromagnetic induction are very simple, they have far-reaching inﬂ uence. Faraday ’ s law is best considered in two interrelated parts: 1 The value of emf induced in a circuit or conductor is directly proportional to the rate of change of magnetic ﬂ ux linking with it. 2 The polarity of such an emf, induced by an increasing ﬂ ux, is opposite to that induced by a decreasing ﬂ ux.