Who constructed the first electromagnet?

• A. Faraday
• B. Davy
• C. Oersted
• D. Ampere

Answer: (A)

An electromagnet is made by passing electric current through a coil wrapped around a piece of iron, which magnetizes the iron and creates a controllable magnetic field. The first practical electromagnet was built by William Sturgeon in the 1820s when he wrapped a coil of wire around an iron bar and connected it to a battery. This showed that magnetic strength could be turned on and off with electricity and could be improved by more turns or higher current. Faraday is famous for uncovering electromagnetic induction—how changing magnetic fields can produce current—not for building the first electromagnet. Oersted demonstrated that current creates a magnetic field, and Ampere and Davy contributed important foundational work in electromagnetism, but the credit for the earliest working electromagnet goes to William Sturgeon.