Question

On April 21, 1820, during a demonstration, Hans Christian Oersted unexpectedly discovered a connection between what two forces of nature, whose separate existence mankind had known about for more than 2000 years without any idea whether or how they might be connected?

Answer 1

Hans Christian Oersted discovered the connection between electricity and magnetism on April 21, 1820, when a compass needle was affected by an electric current; this precipitated the understanding of electromagnetic induction.

Step-by-step explanation:

This finding not only indicated that an electric current has a magnetic effect, but set the stage for later discoveries; just a decade later, in 1831, Michael Faraday and Joseph Henry independently demonstrated that a moving magnet could induce an electric current in a wire, a principle known as magnetic induction.

This symmetry in nature, where electricity can generate magnetic fields and vice versa, became a foundational principle of electromagnetism, leading to revolutionary inventions such as the electric motor and generator, which harnessed these forces to transform human life and technology.