You will have learnt that light is a region of the electromagnetic spectrum. You might not think that light has any connection at all with electricity, magnetism and waves – but it does. Physicists studied these topics for centuries before the connections between them became apparent.
An electric current always gives rise to a magnetic field (this is known as electromagnetism). A magnetic field is created by any moving charged particles such as electrons. Similarly, a changing magnetic field will induce a current in a nearby conductor. These observations led to the unification of the theories of electricity and magnetism by Michael Faraday in the mid-$19th$ century. A vast technology based on the theories of electromagnetism developed rapidly, and continues to expand today (Figure 12.13).
Faraday’s studies were extended by James Clerk Maxwell. He produced mathematical equations that predicted that a changing electric or magnetic field would give rise to transverse waves travelling through space. When he calculated the speed of these waves, it turned out to be the known speed of light.
He concluded that light is a wave, known as an electromagnetic wave, that can travel through space (including a vacuum) as vibrations of electric and magnetic fields. 
Faraday had unified electricity and magnetism; now Maxwell had unified electromagnetism and light. In the $20th$ century, Abdus Salam (Figure 12.14) managed to unify electromagnetic forces with the weak nuclear force, responsible for radioactive decay. Physicists continue to strive to unify the big ideas of physics; you may occasionally hear talk of a theory of everything. This would not truly explain everything, but it would explain all known forces, as well as the existence of the various fundamental particles of matter.