MCQOPTIONS
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MCQOPTIONS
This section includes 244 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
Which D.C. motor is generally preferred for cranes and hoists?%! |
| A. | Series motor |
| B. | Shunt motor |
| C. | Cumulatively compounded motor |
| D. | Differentially compounded motor |
| Answer» B. Shunt motor | |
| 102. |
Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be%! |
| A. | Level compounded |
| B. | Under compounded |
| C. | Cumulatively compounded |
| D. | Differentially compounded |
| Answer» D. Differentially compounded | |
| 103. |
The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is%! |
| A. | 4.0 |
| B. | 2.0 |
| C. | 1.0 |
| D. | 0.5 |
| Answer» E. | |
| 104. |
For a D.C. shunt motor if the excitation is changed%! |
| A. | Torque will remain constant |
| B. | Torque will change but power will remain constant |
| C. | Torque and power both will change |
| D. | Torque, power and speed, all will change |
| Answer» C. Torque and power both will change | |
| 105. |
D.C. generators are normally designed for maximum efficiency around%! |
| A. | Full load |
| B. | Rated r.p.m. |
| C. | Rated voltage |
| D. | All of the above |
| Answer» B. Rated r.p.m. | |
| 106. |
The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. The speed regulation of the motor is%! |
| A. | 2.36% |
| B. | 4.76% |
| C. | 6.77% |
| D. | 8.84% |
| Answer» C. 6.77% | |
| 107. |
A three point starter is considered suitable for%! |
| A. | Shunt motors |
| B. | Shunt as well as compound motors |
| C. | Shunt, compound and series motors |
| D. | All D.C. motors |
| Answer» C. Shunt, compound and series motors | |
| 108. |
In D.C. machines fractional pitch winding is used%! |
| A. | To improve cooling |
| B. | To reduce copper losses |
| C. | To increase the generated e.m.f. |
| D. | To reduce the sparking |
| Answer» E. | |
| 109. |
To get the speed of D.C, motor below the normal without wastage of electrical energy is used.%! |
| A. | Ward Leonard control |
| B. | Rheostat control |
| C. | Any of the above method |
| D. | None of the above method |
| Answer» B. Rheostat control | |
| 110. |
The hysteresis loss in a D.C. machine least depends on%! |
| A. | Frequency of magnetic reversals |
| B. | Maximum value of flux density |
| C. | Volume and grade of iron |
| D. | Rate of flow of ventilating air |
| Answer» E. | |
| 111. |
In a D.C. generator all of the following could be the effects of iron losses except%! |
| A. | Loss of efficiency |
| B. | Excessive heating of core |
| C. | Increase in terminal voltage |
| D. | Rise in temperature of ventilating air |
| Answer» D. Rise in temperature of ventilating air | |
| 112. |
Which D.C. motor will be suitable along with flywheel for intermittent light and heavy loads?%! |
| A. | Series motor |
| B. | Shunt motor |
| C. | Cumulatively compounded motor |
| D. | Differentially compounded motor |
| Answer» D. Differentially compounded motor | |
| 113. |
*$_D.C. generators are normally designed for maximum efficiency around? |
| A. | Full load |
| B. | Rated r.p.m. |
| C. | Rated voltage |
| D. | All of the above |
| Answer» B. Rated r.p.m. | |
| 114. |
*$_The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is? |
| A. | 4.0 |
| B. | 2.0 |
| C. | 1.0 |
| D. | 0.5 |
| Answer» E. | |
| 115. |
*$_Which D.C. motor is generally preferred for cranes and hoists?? |
| A. | Series motor |
| B. | Shunt motor |
| C. | Cumulatively compounded motor |
| D. | Differentially compounded motor |
| Answer» B. Shunt motor | |
| 116. |
*$_Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be? |
| A. | Level compounded |
| B. | Under compounded |
| C. | Cumulatively compounded |
| D. | Differentially compounded |
| Answer» D. Differentially compounded | |
| 117. |
*$_In D.C. shunt motors as load is reduced? |
| A. | The speed will increase abruptly |
| B. | The speed will increase in proportion to reduction in load |
| C. | The speed will remain almost/constant |
| D. | The speed will reduce |
| Answer» D. The speed will reduce | |
| 118. |
*$_The main disadvantage of the Ward-Leonard control method is? |
| A. | High initial cost |
| B. | High maintenance cost |
| C. | Low efficiency at high loads |
| D. | All of the above |
| Answer» E. | |
| 119. |
*$_The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. The speed regulation of the motor is? |
| A. | 2.36% |
| B. | 4.76% |
| C. | 6.77% |
| D. | 8.84% |
| Answer» C. 6.77% | |
| 120. |
*$_A three point starter is considered suitable for? |
| A. | Shunt motors |
| B. | Shunt as well as compound motors |
| C. | Shunt, compound and series motors |
| D. | All D.C. motors |
| Answer» C. Shunt, compound and series motors | |
| 121. |
*$_For a D.C. shunt motor if the excitation is changed? |
| A. | Torque will remain constant |
| B. | Torque will change but power will remain constant |
| C. | Torque and power both will change |
| D. | Torque, power and speed, all will change |
| Answer» C. Torque and power both will change | |
| 122. |
*$_By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor?? |
| A. | Frame |
| B. | Shaft |
| C. | Commutator |
| D. | Stator |
| Answer» D. Stator | |
| 123. |
*/*_Starters are used with D.C. motors because? |
| A. | These motors have high starting torque |
| B. | These motors are not self-starting |
| C. | Back e.m.f. of these motors is zero initially |
| D. | To restrict armature current as there is no back e.m.f. while starting |
| Answer» E. | |
| 124. |
*/*_Which D.C. motor has got maximum self relieving property?? |
| A. | Series motor |
| B. | Shunt motor |
| C. | Cumulatively compounded motor |
| D. | Differentially compounded motor |
| Answer» B. Shunt motor | |
| 125. |
*/*_D.C. motor is to a drive a load which is almost nil for certain part of the load cycle and peak value for short duration. We will select this? |
| A. | Series motor |
| B. | Shunt motor |
| C. | Compound motor |
| D. | Any of the above |
| Answer» D. Any of the above | |
| 126. |
*/*_D.C. motor is to drive a load which has certain minimum value for most of the time and some peak value for short duration. We will select the? |
| A. | Series motor |
| B. | Shunt motor |
| C. | Compound motor |
| D. | Any of the above |
| Answer» B. Shunt motor | |
| 127. |
*/*_D.C. generators are installed near the load centers to reduce? |
| A. | Iron losses |
| B. | Line losses |
| C. | Sparking |
| D. | Corona losses |
| Answer» C. Sparking | |
| 128. |
*/*_The condition for maximum power in case of D.C. motor is? |
| A. | Back e.m.f. = 2 √ó supply voltage |
| B. | Back e.m.f. = I √ó supply voltage |
| C. | Supply voltage =I √ó back e.m.f. |
| D. | Supply voltage = back e.m.f. |
| Answer» C. Supply voltage =I ‚àö√≥ back e.m.f. | |
| 129. |
*/*_The speed of a D.C. shunt motor more than its full-load speed can be obtained by? |
| A. | Decreasing the field current |
| B. | Increasing the field current |
| C. | Decreasing the armature current |
| D. | Increasing the armature current |
| Answer» B. Increasing the field current | |
| 130. |
*/*_Which of the following motors one will choose to drive the rotary compressor?? |
| A. | D.C. shunt motor |
| B. | D.C. series motor |
| C. | Universal motor |
| D. | Synchronous motor |
| Answer» E. | |
| 131. |
*/*_The hysteresis loss in a D.C. machine least depends on? |
| A. | Frequency of magnetic reversals |
| B. | Maximum value of flux density |
| C. | Volume and grade of iron |
| D. | Rate of flow of ventilating air |
| Answer» E. | |
| 132. |
*/*_To get the speed of D.C, motor below the normal without wastage of electrical energy is used.? |
| A. | Ward Leonard control |
| B. | Rheostat control |
| C. | Any of the above method |
| D. | None of the above method |
| Answer» B. Rheostat control | |
| 133. |
*/*_Which D.C. motor will be suitable along with flywheel for intermittent light and heavy loads?? |
| A. | Series motor |
| B. | Shunt motor |
| C. | Cumulatively compounded motor |
| D. | Differentially compounded motor |
| Answer» D. Differentially compounded motor | |
| 134. |
*/*_In a D.C. generator all of the following could be the effects of iron losses except? |
| A. | Loss of efficiency |
| B. | Excessive heating of core |
| C. | Increase in terminal voltage |
| D. | Rise in temperature of ventilating air |
| Answer» D. Rise in temperature of ventilating air | |
| 135. |
*/*_For starting a D.C. motor a starter is required because? |
| A. | It limits the speed of the motor |
| B. | It limits the starting current to a safe value |
| C. | It starts the motor |
| D. | None of the above |
| Answer» C. It starts the motor | |
| 136. |
*/*_In D.C. machines fractional pitch winding is used? |
| A. | To improve cooling |
| B. | To reduce copper losses |
| C. | To increase the generated e.m.f. |
| D. | To reduce the sparking |
| Answer» E. | |
| 137. |
*/*_The armature voltage control of D.C. motor provides? |
| A. | Constant torque drive |
| B. | Constant voltage drive |
| C. | Constant current drive |
| D. | None of the above |
| Answer» B. Constant voltage drive | |
| 138. |
*/*_For constant torque drive which speed control method is preferred?? |
| A. | Field control |
| B. | Armature voltage control |
| C. | Shunt armature control |
| D. | Mechanical loading system |
| Answer» C. Shunt armature control | |
| 139. |
%_If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor_% |
| A. | Of lower H.P. should be selected |
| B. | Of higher H.P. should be selected |
| C. | Can be used for 50°C ambient temperature also |
| D. | Is to be de-rated by a factor recommended by manufacturer and select the next higher H.P. motor |
| Answer» E. | |
| 140. |
%_Which of the following motors is most suitable for signalling devices and many kinds of timers ?_% |
| A. | D.C. shunt motor |
| B. | D.C. series motor |
| C. | Induction motor |
| D. | Reluctance motor |
| Answer» E. | |
| 141. |
%_For the same H.P. rating and full load speed, following motor has poor starting torque_% |
| A. | Shunt |
| B. | Series |
| C. | Differentially compounded |
| D. | Cumulatively compounded |
| Answer» D. Cumulatively compounded | |
| 142. |
%_Which motor has the poorest speed control?_% |
| A. | Differentially compounded motor |
| B. | Cumulatively compounded motor |
| C. | Shunt motor |
| D. | Series motor |
| Answer» E. | |
| 143. |
%_These days D.C. motors are widely used in_% |
| A. | Pumping sets |
| B. | Air compressors |
| C. | Electric traction |
| D. | Machine shops |
| Answer» D. Machine shops | |
| 144. |
%_If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens_% |
| A. | Nothing will happen to the motor |
| B. | This will make armature to take heavy current, possibly burning it |
| C. | This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses |
| D. | Motor will run at very slow speed |
| Answer» D. Motor will run at very slow speed | |
| 145. |
%_In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be_% |
| A. | Almost negligible |
| B. | Rated full-load current |
| C. | Less than full-load current |
| D. | More than full-load current |
| Answer» E. | |
| 146. |
%_When the armature of a D.C. motor rotates, e.m.f. induced is_% |
| A. | Self-induced e.m.f. |
| B. | Mutually induced e.m.f. |
| C. | Back e.m.f. |
| D. | None of the above |
| Answer» D. None of the above | |
| 147. |
_ If a D.C. motor is to be selected for conveyors, which rriotor would be preferred ?$? |
| A. | Series motor |
| B. | Shunt motor |
| C. | Differentially compound motor |
| D. | Cumulative compound motor |
| Answer» B. Shunt motor | |
| 148. |
_ For constant torque drive which speed control method is preferred?$? |
| A. | Field control |
| B. | Armature voltage control |
| C. | Shunt armature control |
| D. | Mechanical loading system |
| Answer» C. Shunt armature control | |
| 149. |
_ The armature voltage control of D.C. motor provides$? |
| A. | Constant torque drive |
| B. | Constant voltage drive |
| C. | Constant current drive |
| D. | None of the above |
| Answer» B. Constant voltage drive | |
| 150. |
_ For which of the following applications a D.C. motor is preferred over an A.C. motor?$? |
| A. | Low speed operation |
| B. | High speed operation |
| C. | Variable speed operation |
| D. | Fixed speed operation |
| Answer» D. Fixed speed operation | |