The Magnetic Effect of an Electric Current

An electric current passing through a wire produces a magnetic field around the wire.
This is known as the magnetic effect of an electric current.
The direction of the magnetic field is dependent on the direction of the current.
The field lines of this magnetic field form concentric circles around the wire.
The strength of the magnetic field increases with an increase in the electric current and decreases as the distance from the wire increases.
The Right-Hand Grip Rule can be used to determine the direction of the magnetic field. If you grip the wire with your right hand and your thumb is pointing in the direction of conventional current, your fingers will curl in the direction of the magnetic field.
A coil of wire, called a solenoid, can be used to enhance the magnetic field. The magnetic field within a solenoid is uniform and strong. Its field lines are parallel and closely spaced inside the coil.
The direction of the magnetic field in a solenoid can be determined by the ‘right-hand grip rule for solenoids’. If your fingers point in the direction of the current, your thumb will point in the direction of the magnetic field inside the coil.
Wrapping a solenoid around an iron core further increases the strength of the magnetic field. This arrangement is known as an electromagnet.
Electromagnets can be switched on and off and the strength of the magnet can be adjusted by changing the current that is flowing.
Electromagnets are used in various practical applications such as loudspeakers, MRI machines, and in the construction of electric motors and generators.