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.
What is DC emf?
A Direct Current (DC) electromagnetic field refers to a constant or static DC electric or DC magnetic field emission which has a frequency of 0 Hz. … DC magnetic fields can also be created from a DC power source of electricity such as battery power, solar power and wind power.
What is induced emf?
Hint: Induced EMF, also known as induced electromotive force, electromagnetic induction, and electromotive force induction is defined as the generation of a potential difference in a coil due to the changes in the magnetic flux through it.
What is back emf in DC motor?
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 starters are required in a DC motor?
Starters are used to protect DC motors from damage that can be caused by very high current and torque during startup. They do this by providing external resistance to the motor, which is connected in series to the motor’s armature winding and restricts the current to an acceptable level.
What is meant by back EMF?
Counter-electromotive force (counter EMF, CEMF), also known as back electromotive force (back EMF), is the electromotive force (voltage) that opposes the change in current which induced it. CEMF is the EMF caused by magnetic induction (see Faraday’s law of induction, electromagnetic induction, Lenz’s law).