Electricity Part - 3

 

                                                     Electricity     

• Effect of electricity on magnet : when a needle magnet is placed in an electric field, the needle is deflected by a force created by electric field. This is called the magnetic effect of electricity. The direction of deflection of needle magnet can be found out by Ampere's swimming formula. 

Ampere's swimming formula :  An imaginary man is swimming spreading his hands over the electric conducting wire in such a way that his head is in the direction of north pole of a needle magnet kept below the conducting wire. In this condition when electric current flows, the north pole of the magnet will be deflected in the direction of the man's left hand. 

 

• Effect of magnet on electricity : When a loose electric conduction wire is hung in the magnetic field of a permanent magnet, the conducting wire is deflected by a force created by the magnet. The direction of deflection of the conduction wire can be found out by Fleming's left hand rule.

Fleming's left hand rule : If left hand's first three fingers are expanded in such a way that they are at right angle with each other and then if fore finger indicates the magnetic field, the middle finger indicates the direction of electric current then thumb will indicate the direction of the deflected conducting wire. 

 

• Barlow's wheel, the simplest motor : There is a hole on a wooden platform between the two arms of a strong horse shoe magnet placed on the platform. Some amount of mercury is kept in the hole. A metal wheel is placed above the mercury in such a way that it can rotate perpendicularly and the wheel's teeth can touch the mercury while rotating. If electric current is flowed according to the circuit(positive pole of a battery-wheel -mercury-negative pole of the battery) denoted by the figure given below, the magnetic field will exert a force to the wheel according to Fleming's left hand rule and the wheel will rotate in a perpendicular plate in a direction denoted by the figure below

Utilizing the main theme of Barlow's wheel and the effect of magnet on electricity, now, AC and DC motor have been developed the figure of those motors are given below