1. State the Faraday’s first law of electromagnetic induction.

Ans:- Whenever a conductor cuts by the magnetic flux an e.m.f is induced in the conductor.

  1. State the Faraday’s second law of electromagnetic induction.

Ans:  – The magnitude of induced e.m.f in the coil is directly proportional  to the rate of change of flux linkage.

  1. What is an electrical generator?

Ans:- An electrical generator is a device (machine) that converts mechanical energy into electrical energy.

  1. What is a motor?

Ans:-  A motor is a device (machine) that converts electrical energy into mechanical energy.

  1. How will you make yoke for small and large machines?

Ans:- For Small machines:- Yoke is made of cast iron

           For Large machines:- Yoke is made of fabricated steel.

  1. What are the main functiond of pole shoes?

Ans:- The pole shoe serves the two purposes; (i) it supports the pole coils and (ii) it spreads the flux and also reduce the reluctance of the magnetic path.

  1. What is the working principle of a dc generator?

Ans:- The working principle of dc generator is electromagnetic induction, i.e. when a conductor cuts across the magnetic field, an emf is induced in it.

  1. What is the function of field system ?

Ans:-  The function of the field system is to produce a uniform magnetic field within which the armature rotates.

  1. What are the functions of armature core?

Ans:-  Armature core serves two functions (i) it houses the armature conductors and (ii) it provides a path of low reluctance to the magnetic flux.

  1. What is armature of a dc machine?

Ans:- Armature is a rotating part of a dc machine where conversion of energy takes place.

  1. Why armature core is of a d.c. machine laminated?

Ans: – In order to reduce eddy current losses.

  1. How can the direction of rotation of a d.c. motor be determined?

Ans: – The direction of rotation of a d.c. motor can be determined by applying Fleming’s left hand rule.

  1. Why carbon brushes are preferred over copper brushes for use in d.c. machines?

Ans: – Due to self lubricating property.