Magnetic Effect of Current

Hans Christian Oersted discovered the magnetic effect of current in 1819 AD.When an electric current is passed through a conductor, it behaves like a magnet. This is called magnetic effect of current.

Magnetic field around a straight wire

The area around which the magnet can influence other bodies by its magnetic force is called magnetic field of a magnet. A current flowing through conducting wire also has a magnetic field around it. To find the magnetic field around the wire carrying current, we can use the right hand thumb rule. According to the rule Thumb points the direction of electric current and the rest of fingers give the direction of magnetic lines of force around the wire. The tangent at any point on the lines of force gives the direction of magnetic field at a point.

Magnetic field around a circular wire

When electric current is passed in a circular wire adjusted as shown in the figure, the iron fittings scattered on the cardboard adjusts in rings, when the board is hit gently. The rings show the lines of force around the wire.

Magnetic lines of force around a solenoid

A spiral adjustment of an insulated wire is solenoid. When electric current is passed in it, It shows two magnetic poles as in a bar magnet. Its poles can be determined by the right hand’s grip rule. It states that if the solenoid is gripped by right hand in such a way that the fingers are in the direction of current flowing in the wire, the thumb will point the north pole of it. The opposite pole will be the south.