Why is back EMF used in DC motors?

Answer:

• The DC motor is a motor that belongs to the class of rotating motors. In DC  motors, the electrical energy is converted into mechanical energy. 
• The production of energy completed depends upon the magnetic field. 
• The DC motors have an advantage over the AC motors because DC motors have a quick starting and stopping mechanism, it has low-cost controls for increasing speed, and the DC motors can very easily pair with gear reducers.
• In the DC motor structure, known as an armature which moves because of the presence of the driving torque. When the armature moves in the magnetic field, the EMF is induced. 
• The EMF induced is very important because it is responsible for converting electrical energy to mechanical energy, making the DC motor self-regulated.