Why the emf generated in the armature of a DC motor is called the back emf?

When the armature of the DC motor rotates under the influence of driving torque, the armature of the conductors moves through a magnetic field inducing an emf in them. The induced emf is in the opposite direction to the applied voltage and is known as the back emf.

Why is the back emf induced in a motor greater when the motor is rotating faster?

As the motor turns faster and faster, the back emf grows, always opposing the driving emf, and reduces the voltage across the coil and the amount of current it draws. If the motor runs at too low a speed, the larger current can overheat it (via resistive power in the coil, P=I2R), perhaps even burning it out.

How the back emf is generated in dc motor?

When armature of dc motor rotates, the armature conductors move through the magnetic field, emf is induced in them. The induced emf acts in opposite direction to applied voltage. This voltage is known as back emf. is converted to mechanical energy and transmitted through shaft.

What is the emf equation of DC motor?

As the armature rotates, a voltage is generated in its coils. In the case of a generator, the emf of rotation is called the Generated emf or Armature emf and is denoted as Er = Eg. In the case of a motor, the emf of rotation is known as Back emf or Counter emf and represented as Er = Eb.

Why back emf is produced?

This back EMF is produced as a result of Lenz’s Law, which says that in a circuit with an induced EMF caused by a change in a magnetic field, the induced EMF causes a current to flow in the direction that opposes the change in flux. Note that the magnetic field lines begin to collapse as the flow of electricity slows.

Why is back EMF produced?

How does velocity affect emf?

The emf is directly proportional to the velocity with which the loop moves between the two regions. Finally, Faraday discovered that an emf is generated around a loop which rotates in a uniform magnetic field of constant strength. In this case, the emf is directly proportional to the rate at which the loop rotates.

How is the speed of a DC motor related to its back EMF and flux?

Back EMF in practice Back EMF is directly related to speed, so when the speed decreases, so does the induced back EMF. From the equation above, we can see that if there is less back EMF, the voltage (and, therefore, current) across the motor will increase.