Explain Oersted's 1820 discovery.

Explanation

**Step-by-Step Solution:**

1. **Introduction to Oersted's Discovery:**
In 1820, Hans Christian Oersted made a groundbreaking discovery that linked electricity and magnetism. He observed that an electric current flowing through a wire produces a magnetic field around it.

2. **Observation of Magnetic Field:**
Oersted conducted experiments where he noticed that when an electric current was passed through a wire, a nearby compass needle would deflect. This indicated that the electric current was creating a magnetic field that influenced the compass.

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