# MCQ in Power Generators (Cells and Batteries) Part 4 | ECE Board Exam

(Last Updated On: May 3, 2019) This is the Multiples Choice Questions Part 4 of the Series in Power Generators, Sources, Principles and Applications as one of the Electronics Engineering topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Exam Questions in Electronics Engineering field, Electronics Books, Journals and other Electronics References.

### MCQ Topic Outline included in ECE Board Exam Syllabi

• MCQ in Cells and Batteries
• MCQ in Electric Generator
• MCQ in Electronic Power Supply
• MCQ in Voltage Regulation
• MCQ in Photovoltaic/Thermoelectric Generator
• MCQ in Distribution Transformer
• MCQ in Uninterrupted Power Supply (UPS)
• MCQ in Float-Battery System
• MCQ in Converters
• MCQ in Inverters

### Continue Practice Exam Test Questions Part 4 of the Series

Choose the letter of the best answer in each questions.

151. The friction and wind age losses in a dc motor depends upon

A. speed

B. armature current

C. flux

D. field and armature resistance

Solution:

152. If a transformer core has air gaps then

A. reluctance of magnetic path is decreased

B. hysteresis loss is decreased

C. magnetizing current is greatly increased

D. eddy current is increased

Solution:

153. The effect of leakage flux in a transformer is to

A. increase copper losses

B. decrease copper losses

C. cause voltage drop in the windings

D. reduce eddy current losses

Solution:

154. The iron losses in a dc motor depend upon

A. flux only

B. speed only

C. both flux and speed

D. temperature

Solution:

155. The greatest percentage of power loss in a dc motor is due to

A. wind age loss

B. core loss

C. copper loss

D. friction loss

Solution:

156. Excessive sparking at the brushes may caused due to

A. dirt on the commutator

B. misalignment of machine

C. loose coupling

D. worn bearings

Solution:

157. The temperature rise of a transformer is directly proportional to

A. apparent power

B. leakage reactance

C. reactive power

D. true power

Solution:

158. A graphical relation between the generated emf and the field current of a machine

A. current generation curve

B. voltage generation curve

C. voltage current curve

D. magnetization curve

Solution:

159. Majority of alternators in use have

A. revolving ac armature winding

B. stationary field type construction

C. revolving field type construction

D. stationary ac armature winding

Solution:

160. The stator of an alternator is identical to that of a

A. dc generator

B. 1 phase induction motor

C. 3 phase induction motor

D. Rosenberg generator

Solution:

161. Excessive motor vibration is caused by

A. too much brush tension

B. open armature coil

C. worn bearings

D. bent shaft

Solution:

162. Hot bearings of a dc motor may be caused by

A. poor ventilation

B. loose coupling

C. incorrect voltage

D. lack of dirty lubricant

Solution:

163. Intermittent sparking at the brushes of dc motor may be caused due to

A. an open armature coil

B. loose coupling

D. incorrect voltage

Solution:

164. When the load on a transformer is increased, the eddy current loss

A. is decreased

B. remains the same

C. is increased

D. becomes zero

Solution:

165. The yoke of a dc machine is made of

A. silicon steel

B. aluminum

C. soft iron

D. cast steel

Solution:

166. The armature of a dc machine is made of

A. silicon steel

B. cast steel

C. wrought iron

D. soft iron

Solution:

167. The voltage per turn of the primary of a transformer is _________ the voltage per turn of the secondary

A. more than

B. the same as

C. less than

D. twice

Solution:

168. The winding of the transformer with greater number of turns will be

A. high voltage winding

B. low voltage winding

C. either high or low voltage winding

D. high power

Solution:

169. The coupling field between electrical and the mechanical systems of a dc machine is

A. electric field

B. both electric and magnetic fields

C. magnetic field

D. electromagnetic field

Solution:

170. The real working Part of a dc machine is the

A. commutator

B. armature winding

C. field winding

D. stator

Solution:

171. Which DC machines are the most common?

A. 2 pole

B. 6 pole

C. 4 pole

D. 8 pole

Solution:

172. The core type transformer provides

A. much longer magnetic pattern

B. lesser average length per turn

C. shorter magnetic path

D. longer magnetic path

Solution:

173. A machine with field excitation by both shunt and series windings

A. complex machine

B. compound machine

C. universal machine

D. shunt/ series machine

Solution:

174. The armature winding of a dc machine is placed on the rotor to

A. save iron

B. facilitate commutation

C. reduce losses

D. reduce armature reaction

Solution:

175. The yoke of a dc machine carries _____ poke flux

A. one third of

B. two times of

C. one half of

D. one fourth of

Solution:

176. The greatest eddy current loss occurs in the __________ of a dc machine

A. field poles

B. commutating process

C. yoke

D. armature

Solution:

177. The commutator pitch for a simplex lap winding is equal to

A. number of poles of the machines

B. 1

C. poles pairs

D. 2

Solution:

178. In a simplex wave winding, the number of parallel paths is equal to

A. number of poles in the machine

B. 2

C. number of pair poles

D. 1

Solution:

179. In a practical transformer, copper losses account for how many percent of the total losses?

A. 75%

B. 25%

C. 85%

D. 95%

Solution:

180. By laminating the core of a transformer, __________ decreases

A. leakage reactance

B. eddy current loss

C. hysteresis loss

D. copper loss

Solution:

181. The number of parallel paths in a simplex lap winding is equal to

A. 2

B. number of poles

C. number of pair poles

D. 1

Solution:

182. In a dc machine the number of commutator segments is equal to

A. number of conductors

B. number of coils

C. twice the number of poles

D. twice the number of coils

Solution:

183. A dc compound generator having full load terminal voltage equal to the no load generator voltage is called __________ generator

A. under compounded

B. flat compounded

C. over compounded

D. un compounded

Solution:

184. The terminal voltage of a __________ generator vary widely with changes in load current

A. series

B. flat compounded

C. shunt

D. over compounded

Solution:

185. The nature of armature winding of a dc machine is decided by

A. front pitch

B. back pitch

C. commutator path

D. number of coils

Solution:

186. The voltage regulation of an alternator is larger than of a dc generator because of

A. large armature resistance

B. large leakage reactance

C. complex effects of armature reaction

D. small armature resistance

Solution:

187. High voltage dc machines use what winding?

A. Lap

B. wave

C. either lap or wave

D. open circuit

Solution:

188. In a lap winding, the number of the brushes required is equal to

A. number of poles

B. commutator pitch

C. number of pairs of poles

D. number of coils

Solution:

189. What is the approximate efficiency of large transformer?

A. 65%

B. 80%

C. 50%

D. 95%

Solution:

190. In a wave winding, the commutator pitch is approximately equal to

A. pole pitch

B. thrice the pole pitch

C. twice the pole pitch

D. half the pole pitch

Solution:

191. A triplex wave winding will have _________ parallel paths

A. 6

B. 4

C. 2

D. 8

Solution:

192. For a given dc generator, the generated voltage depends upon

A. flux only

B. both speed and flux

C. speed only

D. armature rotation

Solution:

193. For the same rating, a dc machine has _________ an ac machine

A. the same weight as

B. less weight than

C. more weight than

D. half the weight than

Solution:

194. Difference between the speed of a rotating magnetic field and the associated rotor

A. split

B. salient pole

C. slip

D. pull out torque

Solution:

195. The field winding of a dc shunt machine usually carries ___________ of the rated current of the machine

A. 2% to 5%

B. more than 20%

C. 15% to 20%

D. less than 0.5%

Solution:

196. A separately excited dc generator is not used because

A. it is costly

B. a separate dc source is required for field circuit

C. voltage drops considerably with load

D. it is bulky

Solution:

197. The effect of armature reaction is to

A. decreased the total flux

B. make the air gap flux uniform

C. increase the total flux

D. make the flux constant

Solution:

198. In a dc generator armature reaction __________ pole tip

A. weakens the flux at the trailing

B. weakens the flux at the leading

C. strengthens the flux at the leading

D. strengthens the flux at the trailing

Solution:

199. The greatest percentage of the heat loss in a dc machine is due to

A. eddy current loss

B. copper loss

C. hysteresis loss

D. frictional loss

Solution:

200. The size of a dc generator can be reduced by using

A. lap winding

B. high resistance winding material

C. iron commutator

D. magnetic material of high permeability

Solution:

### Questions and Answers in Power Generators, Sources, Principles, Applications

Following is the list of practice exam test questions in this brand new series:

MCQ in in Power Generators, Sources, Principles, Applications
PART 1: MCQs from Number 1 – 50                        Answer key: PART 1
PART 2: MCQs from Number 51 – 100                   Answer key: PART 2
PART 3: MCQs from Number 101 – 150                 Answer key: PART 3
PART 4: MCQs from Number 151 – 200                 Answer key: PART 4
PART 5: MCQs from Number 201 – 250                 Answer key: included
PART 6: MCQs from Number 251 – 300                 Answer key: included
PART 7: MCQs from Number 301 – 350                 Answer key: included
PART 8: MCQs from Number 351 – 400                 Answer key: included
PART 9: MCQs from Number 401 – 450                 Answer key: included
PART 10: MCQs from Number 451 – 500                 Answer key: included