Who is credited with discovering that a current in a wire produces a magnetic field?

Who is credited with discovering that a current in a wire produces a magnetic field?

• A. Hans Christian Oersted
• B. Albert Einstein
• C. Marie Curie
• D. Thomas Edison

Answer: (A)

Electric current creates a magnetic field. This idea came to light when Hans Christian Oersted observed that a compass needle deflected whenever a current flowed through a nearby wire. The deflection showed that the moving electric charges produced a magnetic field around the wire, wrapping in circles around it. The direction of the field around a straight wire can be understood with the right-hand rule: if you point your thumb along the current, your fingers curl in the direction of the magnetic field. This discovery connected electricity and magnetism for the first time, laying the groundwork for the whole field of electromagnetism and technologies like motors and transformers that rely on magnetic fields produced by currents. The other figures listed made important contributions in different areas—Einstein in relativity and quantum ideas, Curie in radioactivity, Edison in practical electrical invention—but they did not discover this fundamental link between electricity and magnetism.

Electric current creates a magnetic field. This idea came to light when Hans Christian Oersted observed that a compass needle deflected whenever a current flowed through a nearby wire. The deflection showed that the moving electric charges produced a magnetic field around the wire, wrapping in circles around it. The direction of the field around a straight wire can be understood with the right-hand rule: if you point your thumb along the current, your fingers curl in the direction of the magnetic field.

This discovery connected electricity and magnetism for the first time, laying the groundwork for the whole field of electromagnetism and technologies like motors and transformers that rely on magnetic fields produced by currents. The other figures listed made important contributions in different areas—Einstein in relativity and quantum ideas, Curie in radioactivity, Edison in practical electrical invention—but they did not discover this fundamental link between electricity and magnetism.