- 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.
- 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.
- What is an electrical generator?
Ans:- An electrical generator is a device (machine) that converts mechanical energy into electrical energy.
- What is a motor?
Ans:- A motor is a device (machine) that converts electrical energy into mechanical energy.
- 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.
- 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.
- 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.
- 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.
- 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.
- What is armature of a dc machine?
Ans:- Armature is a rotating part of a dc machine where conversion of energy takes place.
- Why armature core is of a d.c. machine laminated?
Ans: – In order to reduce eddy current losses.
- 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.
- Why carbon brushes are preferred over copper brushes for use in d.c. machines?
Ans: – Due to self lubricating property.