Chapter 12 · Question 2

Describe the experiment of Hans Christian Oersted. What conclusion did he draw from his observation, and why was this discovery significant?

Answer Revealed

Direct Answer:

Oersted placed a straight thick copper wire perpendicular to the plane of paper in an electric circuit. He placed a small compass near the wire and passed current through the circuit by inserting a key. He observed that the compass needle deflected. This showed that an electric current flowing through a metallic conductor produces a magnetic effect, establishing that electricity and magnetism are linked. His research later led to technologies such as radio, television, and fibre optics.

Simple Explanation

In 1820, Oersted accidentally discovered something remarkable. He passed electric current through a copper wire and noticed that a compass needle placed nearby got deflected. Before that, people thought electricity and magnetism were completely separate things. His observation proved they are linked — a moving electric charge creates a magnetic field. This was a huge deal because virtually every electromagnetic technology we use today, from speakers to MRI machines, traces back to this insight.

Exam-Ready Structure

Hans Christian Oersted's accidental discovery in 1820 is the historical foundation of electromagnetism, observed through the simple Activity 12.1 described in the NCERT textbook. 1. Experimental setup (Activity 12.1): (a) Take a straight thick copper wire and place it between points X and Y in an electric circuit. The wire XY is kept perpendicular to the plane of paper. The circuit includes a resistor, an ammeter, a plug key, and a battery. (b) Horizontally place a small compass needle near the copper wire and observe its position. (c) Insert the key into the plug to pass current through the circuit. (d) Observe the change in the position of the compass needle. 2. Observation: On passing electric current through the metallic conductor, the compass needle is deflected. 3. Conclusion: The electric current through the copper wire produces a magnetic effect. This proved that electricity and magnetism are linked to each other — a current-carrying wire behaves like a magnet. 4. Historical significance: Oersted was one of the leading scientists of the 19th century who played a crucial role in understanding electromagnetism. His discovery that electricity and magnetism are related phenomena later paved the way for technologies such as radio, television, and fibre optics. The unit of magnetic field strength, the oersted, is named in his honour. 5. Extension: The chapter builds on this discovery to explore the reverse possibility — an electric effect of moving magnets — studying magnetic fields, electromagnets, and electromagnetic effects.

Key Points

Oersted (1820): compass needle deflected when current passed through a nearby wire
Setup: straight copper wire perpendicular to paper plane, compass placed nearby
Observation: current-carrying wire behaves like a magnet — produces magnetic effect
Conclusion: electricity and magnetism are linked (electromagnetism)
Legacy: led to radio, television, fibre optics; unit of magnetic field is the oersted

Describe the experiment of Hans Christian Oersted. What conclusion did he draw from his observation, and why was this discovery significant?