ABSTRACT
This chapter explains important concepts of electromagnetism. It aims to apply the screw rule to determine direction of a magnetic field. The chapter suggests that the magnetic field around a solenoid is similar to a magnet. The solenoid is very important in electromagnetic theory since the magnetic field inside the solenoid is practically uniform for a particular current, and is also versatile, inasmuch that a variation of the current can alter the strength of the magnetic field. An electromagnet, based on the solenoid, provides the basis of many items of electrical equipment, examples of which include electric bells, relays, lifting magnets and telephone receivers. The chapter describes practical applications of an electromagnet that is electric bell, relay, lifting magnet, telephone receiver. It also describes the principle of operation of a simple direct current motor. The chapter examines the principle of operation and construction of a moving coil instrument.
