Electricity and magnetism were thought to be entirely distinct phenomena prior to the 19th century. Charges and currents were used to study electricity, whereas magnets and magnetic fields were used to explain magnetism.
But in 1820, Danish physicist and chemist Hans Christian Oersted produced a groundbreaking discovery that fundamentally altered this idea. His well-known experiment laid the groundwork for the study of electromagnetism by demonstrating the close relationship between electricity and magnetism.
Background
Oersted taught at the University of Copenhagen as a professor. He used a wire that was attached to a battery to illustrate the heating effect of electric current during one of his lectures in 1820.
He discovered by accident that whenever electricity passed across the wire, a magnetic compass needle put nearby deflected. The needle went back to its initial north-south orientation after the current stopped. One of the most significant physics discoveries was this surprising revelation.
The Experimental Setup
Oersted’s experimental arrangement was simple yet brilliant. It consisted of:
1. A “straight conducting wire” that is attached to a “battery” and a “key” to regulate the current flow.
2. A needle from a magnetic compass positioned either above or below the wire.
The wire was aligned along the north-south direction and positioned parallel to the magnetic needle. In order to permit current to pass through the wire, Oersted then closed the circuit.
Observation
When the circuit was completed, Oersted observed that:
There was a deviation from the typical north-south direction of the compass needle. The needle’s direction of deflection changed as the current’s direction changed. The needle reverted to its initial north-south orientation when the current was cut off.
This suggested that the area surrounding the wire experienced a magnetic effect as a result of the electric current.
Conclusion of the Experiment
Oersted presume from his studies that a conductor carrying current creates a magnetic field surrounding it. A nearby magnetic needle is subjected to force from this field, which causes it to deflect. Oersted made the first experimental connection between electricity and magnetism as a result.
With this discovery, electromagnetism was born, demonstrating that magnetic fields could be produced by electric current.
Explanation of the Phenomenon
A magnetic field is produced in the area around a conductor when an electric current passes through it. The Right-Hand Thumb Rule can be used to determine the direction of this magnetic field:
The fingers will curl in the direction of the magnetic field lines around the conductor if the conductor is held in the right hand with the thumb pointing in the direction of the current.
This rule makes it easier to see how the wire is surrounded by concentric circles of magnetic field lines.
Significance of Oersted’s Experiment
Oersted’s discovery had a profound impact on science and technology. Its significance can be understood as follows:
Birth of Electromagnetism: The experiment showed that electricity and magnetism are interrelated, forming the basis of electromagnetic theory.
Foundation for Ampère’s Law: André-Marie Ampère expanded Oersted’s findings to establish mathematical relationships between current and magnetic fields, known as Ampère’s Circuital Law.
Inspiration for Faraday’s Work: Oersted’s discovery inspired Michael Faraday to explore the reverse effect — the production of electric current from changing magnetic fields, leading to the discovery of electromagnetic induction.
Development of Electromagnetic Devices: The principle demonstrated by Oersted is used in various devices like electric motors, galvanometers, ammeters, and compasses.
Foundation of Modern Physics: Oersted’s experiment was the first step toward the unification of forces, later mathematically described by James Clerk Maxwell in his famous equations of electromagnetism.
Modern Understanding
Today, the idea of magnetic field lines is used to explain Oersted’s experiment. The compass needle receives a torque as a result of the magnetic field produced by the current, which causes it to deflect. The amount of current flowing through the conductor, its distance from the wire, and the surrounding medium all affect the field’s strength and direction.
Summary
A new era in physics was accompanyed in by Hans Christian Oersted’s straightforward’s revolutionary experiment in 1820. It established the close relationship between electricity and magnetism by offering the first concrete proof that electric currents produce magnetic fields.
In addition to altering our scientific knowledge, this discovery sparked useful products that run our contemporary society, including as communication networks and electric motors and generators.
