CBSE Class-12 Compartment Exam 2019 : Question Paper-Electrical Machines
I. Attempt any ten questions :
1. No load current of a transformer
(a) has small magnitude with high p.f.
(b) has high magnitude with low p.f.
(c) has high magnitude with high p.f.
(d) has small magnitude with low p.f.
2. In a transformer, which of the following windings has got more cross-sectional area ?
(a) Primary winding
(b) Secondary winding
(c) High voltage winding
(d) Low voltage winding
3.Cross-section of the iron core of a transformer is approximately circular.
This is done because
(a) It is easy to assemble circular core
(b) It is easy to prepare circular coil
(c) Electromagnetic forces tend to make coil circular
(d) All of the above reasons
4. Iron losses in a d.c. motor are independent of variation in
(d) speed and voltage