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explain dc motar?
A d.c. motor works on the principle that when an electric current is passed through a conductor placed normally in a magnetic field, a force acts on the conductor as a result of which the conductor begins to move and mechanical energy (or work) is obtained. The direction of force is obtained with the help of Fleming’s left hand rule.
 The basic structure of an electric motor is shown in figure below.

The main parts of  an electric motor are :

(i) The armature coil ABCD mounted on an axle.
(ii) The split parts S1 and S2 of a ring known as commutator (that is a slip ring made of copper is divided in two parts S1 and S2),
(iii) A pair of carbon (or copper) brushes B1 and B2, and 
(iv) A horse- shoe electromagnet NS.
The armature coil ABCD is wound around a soft iron core and it is placed in between the pole pieces of a strong horse shoe electromagnet NS. The coil is free to rotate about its axis. The ends of the coil A and D are respectively connected to the split parts S1 and S2 of a ring. The brush B1 presses lightly against the split ring S1 and the brush B2 presses lightly against the split ring S2. A d.c. source (that is , battery) is connected across the brushes B1 and B2 through a key and rheostat. When the coil rotates, the split parts of ring rotate with it, while the brushes which are fixed, remain at their position and keep touching the split ring all the time.
A wheel can be mounted on the axle attached to the armature coil along its axis so as to rotate the desired part of the machine where the motor is used.


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