* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download bee-material-new-microsoft-office-powerpoint
Commutator (electric) wikipedia , lookup
Brushless DC electric motor wikipedia , lookup
Pulse-width modulation wikipedia , lookup
Power inverter wikipedia , lookup
Opto-isolator wikipedia , lookup
Power factor wikipedia , lookup
Stray voltage wikipedia , lookup
Electrical substation wikipedia , lookup
Electric power system wikipedia , lookup
Wireless power transfer wikipedia , lookup
Amtrak's 25 Hz traction power system wikipedia , lookup
Three-phase electric power wikipedia , lookup
Power electronics wikipedia , lookup
Buck converter wikipedia , lookup
Electric motor wikipedia , lookup
Magnetic core wikipedia , lookup
Transformer wikipedia , lookup
Distribution management system wikipedia , lookup
Stepper motor wikipedia , lookup
History of electric power transmission wikipedia , lookup
Voltage optimisation wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Rectiverter wikipedia , lookup
Electrification wikipedia , lookup
Mains electricity wikipedia , lookup
Brushed DC electric motor wikipedia , lookup
Power engineering wikipedia , lookup
Variable-frequency drive wikipedia , lookup
Resonant inductive coupling wikipedia , lookup
Alternating current wikipedia , lookup
2. In a dc generator the initial flux is produced due to a) The saturation of the core b) residual magnetism c) eddy currents d) hysteresis. 1. The flux produced by the field winding in a DC machine. a) rotates at a synchronous speed with respect to the stator. b) rotates at a speed less than the synchronous speed with respect to the stator. c) rotates at a speed higher than the synchronous speed with respect to the stator. d) is stationary with respect to the stator. 3. Which of the following is the cause of production of torque in a dc motor. a) The resultant flux due to the field and armature currents a) the flux due to field currents b) the flux due to armature current c) none of these. 4. The emf generated in a dc motor is called back emf because. a) It is generated in the armature. b) it opposes the direction of rotation of the motor. c) it is in a direction opposite to that of the applied voltage a) none of these. 5. Which of the following is an appropriate classification of induction motors a) Slip ring b) squirrel cage c) wound rotor d) all of these 6. In the shell type construction of transformer which of the following is not correct. a) Each limb carries the primary and secondary b) windings are sandwiched. c) the low voltage winding is placed nearer to the core. a) all of these. 7. The short circuit test is conducted to determine. a) Power factor at short circuit b) series parameters c) efficiency d) regulation. 8. The purpose of voltage regulation of a transformer is to a) Maintain the voltage within the prescribed limits. b) control the power consumption c) control power theft d) all of the above. 9. The root mean square of an alternating quantity is another name for its a) Instantaneous value b) peak value c) effective value d) average value 10. If the number of poles in an ac generator is doubled and its speed halved, the frequency of the induced emf a) Is halved b) remains unchanged c) is doubled d) is quadrapuled 11. The form factor of a rectangular wave is equal to a) 1.0 b) 1.11 c) 1.15 d) 1.414 12. The unit of reactive power is a) Wattt b) VAR c) volt ampere d) none of the above 13. The power consumed in a pure inductive circuit a) Zero b) VmIm/2 c) VI d) IL 14. Reactive power in a circuit signifies a) Energy consumed by the magnetic/electric field b) Energy consumed by the resistance of inductance and capacitance c) Energy exchanged between the magnetic/electric field and the source d) Energy consumed by the resistance in the circuit. 15. In a series RLC circuit, resonance occurs at a) L=C b) R=C c) R=L d) Xl=Xc 16. Super position theorem can be employed to a) Voltages only b) currents only c) power only d) all of the above 17. Thevenin,s theorem can be applied to networks containing a) Passive elements only b) active elements c) linear elements only d) all of the above 18. Which of the following theorems helps in simplifying computations when the load across a circuit is varying a) Superposition b) Nortons c) Thevenins d) Maximum power transfer 19. One farad is equal to a) 1Ω b) 1V/C c) 1C/V d) none of the above 20. The unit of resistivity is a) Ω b) Ω/m c) Ω/m2 d) Ωm