Electromagnetism : DC Motor

In your childhood,you probably seen this small machine runs your toys and remote control cars. When the battery run out,this machine stops run and you open the toy and see this small machine and you repair it like a mechanic!! This small cute machine called 'DC Motor' or a 'Conduction Motor'

DC(Direct Current ) motor runs in direct current like from batteries. This DC Motor have many parts. Armature,Permanent magnet,commutator,carbon brush and coils or winding.

Function of DC Motor parts :

1) Stator magnet 
 
   =Produce magnetic field

2) Winding         
=The winding made of copper wind around the armature slot. The winding produce a magnetic filed when the current flows through the copper winding.This produce opposite magnetic field and cut the magnetic flux and rotates the armature.

3) Armature :
   =The armature is the rotating part of the motor and wind a copper conductor along the armature slot.

4)Commutator :
   =Supply DC current by commutator to armature winding.

5) Carbon brush :

=Distribute DC supply and send to the carbon brush.the carbon brush emit a small amount  if spark on the commutator by friction.that shows the carbon brush distribute power for every rotation per second.

Working principle of DC Motor :

In the picture above shown,a DC power supply given to the carbon brush.This carbon brush will distribute power to the commutator.The DC current flows through the armature winding. this winding will produce magnetic field around the armature. this armature winding produce opposite magnetic poles. This will produce torque or force. In the permanent magnet,there's north pole and south poles. between the poles there's magnetic line as the picture shown in green color line. 

When the current pass through the conductor,it produce the opposite magnetic field that rotates the motor. The permanent magnet poles are N-S and the conductor magnetic field poles S-N. In normal magnet,Similar pole repel and different pole attract.The same thing goes on here. The similar pole repel and move the other side of the pole and attract then repel again.When the north pole attract the south pole from armature winding,the motor won't rotate and stop at 180° rotation. To avoid happen this,commutator will flip the armature for each rotation and rotate to 360° by move freely.

 Now the motor rotate in forward. So to make the motor rotate backward, the polarity (terminal of DC Motor) Change to - (negative) to + (positive). So the motor will rotate in backward. When the motor rotate backward, the armature winding produce magnetic field like north pole to south pole. so this will attract the opposite pole and produce torque.

To determine the rotation of the rotor Fleming's left hand rule and right and grip rule are used. The Fleming's left hand rule will determine the the rotation of the motor while the right hand grip rule will determine the direction of the magnetic field.

 

 Right hand grip rule

Fleming's left hand rule

 

Now you know the secrets behind your toys. Try open your toys and dismantle the DC motor. You will easily understand the parts of it. It's simple and easy