Magnetic Effect of Electric Current

Magnetic Effect of Electric Current

When electric current flows through a wire wound around an iron bar, the bar behaves like a magnet. This magnet is called an electromagnet.
An electromagnet is formed due to the magnetic effect of electric current. This magnetic effect of electric current was discovered by Hans Christian Oersted. Once, while preparing for a lecture, he noticed that there was a deflection in the needle of a magnetic compass kept near a wire that was connected to a battery. This deflection occurred every time the battery was switched on and off. He realised that a magnetic field is created around a current-carrying wire in a circuit.

Magnetic Effect of Electric Current

Magnetic Effect of Electric Current

Magnetic Effect of Electric Current

Magnetic Effect of Electric Current

a) Direct current (DC):-  A current that always flows in one direction

only is called direct current. The current we get from a battery is a direct current.

 

b) Alternating current (AC):- A current that reverses its direction periodically is called alternating current. Most power stations in our country produce alternating current. AC changes direction every 1/100 second and its frequency is 50 Hertz (Hz).

One advantage of AC over DC is that it can be transmitted over long distances without much loss of energy.

 

A solenoid is a circular coil of wire in the shape of a cylinder.

When current flows through a solenoid, it behaves like a bar magnet. The ends of the solenoid behaves like the North and South poles of a magnet. The magnetic field produced by a solenoid is similar to the magnetic field produced by a bar magnet.

The strength of the magnetic field depends upon the strength of the current and the number of turns of the coil.

 

Electromagnet:-   A strong magnetic field inside a solenoid can be used to magnetise a piece of magnetic material like a soft iron when placed inside the coil. Such a magnet is called an electromagnet. If electric current is passed through a wire wound around a piece of soft iron, it behaves like a magnet. Such a magnet is called an electromagnet.

 

Force on a conductor carrying current in a magnetic field:-

A.M.Ampere suggested that if a current carrying conductor produces a magnetic field and exerts a force on a magnet, then a magnet should also exerts a force on a current carrying conductor.

Eg:- If an aluminium rod is suspended horizontally by a wire between the poles of a horse shoe magnet and current is passed through the wire, then the aluminium rod is displaced. If the direction of current is reversed, the direction of displacement is also reversed. The force exerted is maximum if the conductor is perpendicular to the magnetic field.