Magnetic Field Produced by an Electric Current
A magnetic field is produced not only around a magnet but also around a wire carrying an electric current. This can be observed by watching the needle of a compass rotate when the compass is placed near a current-carrying wire.
Magnetic Field Produced by a Circular Coil
- Battery: Supplies electric current to the coil.
- Wire: Represents a coil made by winding a wire several times. When electric current flows through the coil, a magnetic field is formed around it.
- Compass: Shows the direction of the magnetic field produced by the coil. The needle of each compass rotates to align with the direction of the magnetic field at its location.
- Right hand: Illustrates the right-hand grip rule applied to a coil. When the four fingers of the right hand curl in the direction of the current flowing through the coil, the thumb points in the direction of the magnetic field inside the coil and toward the coil’s north pole.
The magnetic field of a coil is generally similar to that of a bar magnet. Inside the coil, the magnetic field is directed along the axis of the coil and is relatively uniform. Outside the coil, the magnetic field lines curve around and return toward the opposite pole. Therefore, compasses placed around the coil point in different directions depending on their positions.