In Chapter 4, it was established that an electric current generates a magnetic field and that two current-carrying wires exert a magnetic force on each other. In Chapter 6, it was established that a magnetic field changing with time gives rise to an electric field. Chapter 8, on the other hand, shows that the converse is also true, i.e., an electric field changing with time results in a magnetic field. James Clerk Maxwell (1831-1879) theorised that this was indeed true. While applying Ampere’s circuital law to find the magnetic field at a point outside a charging capacitor connected to a time-varying current, Maxwell found that something was amiss. He theorised the possibility of a new current called the displacement current to fill the gap in Ampere’s circuital law. Maxwell derived a set of equations involving electric and magnetic fields, their sources, the charge and current densities. These equations are known as Maxwell’s equations. Maxwell’s equations led to the discovery of electromagnetic waves other than just the visible light rays. This chapter covers electromagnetic waves, their sources and nature, derivation of displacement current, the electromagnetic spectrum and the types of waves.