Electromagnetic induction was discovered by

• A. Joule
• B. Isaac Newton
• C. Galvani
• D. Faraday

Answer: (D)

A changing magnetic environment can produce electricity. Faraday showed this unmistakably by moving a magnet through a coil (or moving the coil in a magnetic field), which generates an electromotive force in the circuit. This is the essence of electromagnetic induction: the induced emf depends on how quickly the magnetic flux through the loop changes.

This discovery gave us Faraday’s law, which says the induced emf equals the negative rate of change of magnetic flux through the loop. The minus sign reflects Lenz’s law: the induced current creates a magnetic field that opposes the change that caused it. The idea behind induction is fundamental to how generators and transformers work.

Other scientists mentioned contributed to related electrical ideas, but induction—the creation of current from a changing magnetic field—is attributed to Faraday.