In which year did Hans Christian Oersted discover that a compass needle gets deflected when an electric current passes through a metallic wire placed nearby?

The correct answer is 1820.

Step-by-Step Explanation:

1. Historical Context: Hans Christian Oersted, a Danish physicist and chemist, discovered the fundamental relationship between electricity and magnetism, creating the field of electromagnetism.

2. The Discovery: In April 1820, while preparing for a lecture, Oersted set up an experiment demonstrating that an electric current flowing through a metallic wire caused a nearby magnetic compass needle to deflect from magnetic north.

3. Significance: This landmark experiment in 1820 proved for the first time that electric currents create surrounding magnetic fields, laying the foundation for modern electrodynamics and electromagnetic theory.