You are here
Magnetic Effect of Current
- Electric current can produce magnetism
- A current-carrying wire acts like a magnet
- This is the magnetic effect of current
- It is used in many devices
- Discovered by Hans Christian Oersted
Example 1 — Oersted's compass
- current passes in a wire
- a nearby compass needle deflects
- shows the wire made a magnetic field
Example 2 — Devices using it
- electric bells and motors
- electric fans and loudspeakers
- all use the magnetic effect
Important Points
- A compass needle is a tiny magnet, so its deflection proves a magnetic field exists.
- When the current stops, the magnetism produced by the wire disappears.
- The magnetic field is increased by using a coil instead of a straight wire.
Definition — Magnetic Effect of Current
The magnetic effect of current means that a current-carrying wire behaves like a magnet and produces a magnetic field around it.
Materials needed
A thick insulated copper wire AB, a compass, a cell, a switch, connecting wires.
Procedure
Fix wire AB in the north-south direction with a compass placed under it.
Keep the switch open first, then close it so current flows in AB.
Keep the switch open first, then close it so current flows in AB.
Observation
With switch open, the needle stays north-south. With switch closed, the needle deflects.
Explanation
The deflection proves the current-carrying wire made a magnetic field, which moved the compass needle.
◆ Summary
- Open switch: no deflection.
- Closed switch: needle deflects.
- Current makes a magnetic field.
🌍 Earth is a Giant Magnet
Magnetism from the core.
The Earth behaves like a giant magnet because of electric currents from molten iron in its outer core. Its magnetic field protects the planet from harmful Sun particles, creates the Aurora (Northern and Southern Lights), and is used by humans for navigation and by animals like the garden warbler and sea turtles for migration.
Objective Type Questions Q1(a) - Page 69 Lakhmir Singh
Question
Name the following: The scientist who discovered the magnetic effect of current.
Show answer
Hans Christian Oersted
Explanation
- He found a compass needle deflects near a current-carrying wire.
Objective Type Questions Q2(c) - Page 69 Lakhmir Singh
Question
Fill in the blank: An electric current flowing in a wire produces a ________ effect.
Show answer
magnetic
Explanation
- A current-carrying wire behaves like a magnet.
Multiple Choice Questions Q7 - Page 71 Lakhmir Singh
Question
The magnetic effect of electric current was discovered by:
- (a) Maxwell
- (b) Darwin
- (c) Oersted
- (d) Newton
Show answer
(c) Oersted
Explanation
- Oersted observed a compass deflect near a current-carrying wire.
