Ask now - it's free
in Electrical Engineering by

Know someone who can answer this question ? Share this on Facebook Twitter Whatsapp

← Prev Question Next Question →

1 Answer

0 like 0 dislike

Back emf: When the armature of DC motor rotates under the fixed magnetic field and cuts it, by Faraday's law an emf is induced in them. The induced emf acts in opposite direction to the applied voltage as per Lenz’s law. Hence known as back or counter emf Eb.

The significance of back emf: 

i) If the motor is at standstill or rest Eb is zero. This causes large current flow through armature, which produce high starting torque. ii) When motor takes speed, the back emf increases, causes armature current to decrease hence decrease in torque. iii)It follows therefore that back emf in DC motor regulates the flow of armature current i.e. it automatically changes the armature current to meet load requirements. 

Related questions

0 answers 2,054 views
0 answers 37 views
0 answers 106 views
1 answer 28 views
1 answer 47 views
0 answers 21 views
0 answers 48 views

Want to ask a new question ? :-> Ask Question

Want to help the community by giving answer? :-> Unanswered Questions

Here anyone can ask and answer any question. Get help and can help to any engineering problem including Electrical, Electronics, Mechanical, Telecommunication, Instrumentation, Computer, Mathematics, Physics etc. Get answers to questions. Help is always 100% free!