6.1. INTRODUCTION

Electricity and magnetism were considered separate and unrelated phenomena for a long time. In the early decades of the nineteenth century, experiments on electric current by Oersted, Ampere and a few others established the fact that electricity and magnetism are inter-related.

For many years, people believed that electricity and magnetism were two distinct forces. However, experiments conducted by scientists like Oersted and Ampere revealed that they are actually interconnected. For example, when an electric current passes through a wire, it creates a magnetic field around it. This realization laid the groundwork for understanding how these two forces interact.

Think of electricity and magnetism like two siblings who initially play separately. Once they discover that they can work together, like in a game, they create a more powerful experience—just as electric currents and magnetic fields enhance each other's effects in technology.

They found that moving electric charges produce magnetic fields. For example, an electric current deflects a magnetic compass needle placed in its vicinity.

Scientists discovered that not only does electricity create magnetism, but moving magnetic fields can also produce electric current. For instance, when current flows through a wire near a compass, the compass needle moves, indicating that a magnetic field is present. This interaction raises important questions regarding the possible reverse process—whether moving magnets can generate electric currents.

Imagine stirring a spoon in a cup of tea. The spoon (the moving magnetic field) creates ripples in the tea (the electric current), showing that movement in one can influence the other.

The experiments of Michael Faraday in England and Joseph Henry in USA, conducted around 1830, demonstrated conclusively that electric currents were induced in closed coils when subjected to changing magnetic fields.

Faraday and Henry conducted key experiments that established the principle of electromagnetic induction. They showed that when a magnetic field changes around a coil of wire, it can create (or 'induce') an electric current in that coil. This discovery was fundamental to the development of technologies such as generators and transformers, which rely on this principle.

Consider riding a bicycle with a dynamo. As the wheels (magnetic field) turn, they generate electricity that lights up the bicycle lights (the induced current). This everyday example illustrates the principles outlined by Faraday and Henry in their groundbreaking experiments.

The phenomenon in which electric current is generated by varying magnetic fields is appropriately called electromagnetic induction.

Electromagnetic induction is not only a fundamental concept in physics but also the backbone of many modern technologies. The ability to generate an electric current through changing magnetic fields has led to the development of various devices that form the foundation of our electrical infrastructure, including household appliances and industrial machinery.

Think of a wind turbine. As the wind (a moving magnetic field) turns the blades (the closed loops of wire), it generates electricity. This demonstrates how terrestrial forces can be harnessed for practical purposes, making the concept of electromagnetic induction both valuable and essential.

The pioneering experiments of Faraday and Henry have led directly to the development of modern day generators and transformers. Today’s civilisation owes its progress to a great extent to the discovery of electromagnetic induction.

Thanks to the discoveries stemming from electromagnetic induction, we see practical applications in countless daily technologies, from power generation (electricity supplied to homes and industries) to transformers that adjust voltage levels for different uses. Our entire electric grid and much of our technology rely on these principles.

When you flip a switch to turn on a light, the electricity that lights your room is generated through a complex network dependent on electromagnetic induction. Just like magic, a simple action brings light into your life, revealing the profound impact of Faraday and Henry’s findings.

--