Synopsis of Electrical Engineering

Important Multiple Choice Questions On Power Systems 1. With 100 % inductive shunt compensation, the voltage profile is flat for 100% loading line 50% loading line Zero loading of line None of these 2. For a long uncompensated line the limit to the line loading is governed by Thermal limit Voltage drop Stability limit Corona loss 3. Series capacitive compensation in EHV transmission lines is used to Reduce the line loading Improve   the stability of the system Reduce the voltage profile Improves the protection of the line 4. The main consideration for higher and higher operating voltage of transmission is to Increase the efficiency of transmission Reduce power losses Increase power transmission capability Both (A) and (B) above 5. The inertia constant H of a machine of 200MVA is 2 p.u. its value corresponding to 400MVA will be 4 2 1 0.5 6. A 500MVA, 11kV synchronous generator has 0.2 p.u. synchronous re

Important Multiple Choice Questions in Electrical Machines 1.        In a shaded pole induction motor, the rotor runs from the A)      Shaded portion to the unshaded portion of the pole while the flux in the former leads that of the latter B)       Shaded portion to the unshaded portion of the pole while the flux in the former lags that in the latter C)       Unshaded portion to the shaded portion while the flux in the former leads that it in the latter D)      Unshaded portion to the shaded portion  while the flux in the former lags that in the latter 2.        The torque of a reluctance motor can be effectively increased by A)      Increasing reluctance of the magnetic circuit along the direct axis B)       Decreasing the reluctance of the magnetic circuit along the quadrature axis C)       Increasing the ratio of the quadrature axis reluctance to direct axis reluctance D)      Decreasing the ratio of quadrature axis reluctance to direct axis reluctance 3.  

Important Multiple Choice Questions in Electrical Circuits 1.        If a capacitor is energised by a symmetrical square wave current source, then the steady state voltage across the capacitor will be A)      Square wave B)       Triangular wave C)       Step wave D)      Impulse wave 2.        If the step response of an initially relaxed circuit is known, then the ramp response can be obtained by A)      Integrating the step response B)       Differentiating the step response C)       Integrating the step response twice D)      Differentiating the step response twice 3.        A water boiler of home is switched on to the AC mains supplying power at 230V/50Hz. Th frequency of instantaneous power consumed by the boiler is A)      0 Hz B)       50 Hz C)       100 Hz D)      150 Hz 4.        In a series RLC high Q circuit, the current peaks at a frequency A)      Equal to the resonant frequency B)       Greater than the resonant frequency C)      

Important Multiple Choice Questions From Electrical and Magnetic Fields 1.        Transmission of power to a load over transmission line achieves optimum value when standing-wave ration (SWR) becomes A)      2:1 B)       1:2 C)       1:1 D)      1:4 2.        White noise is that signal whose frequency spectrum A)      Extends over infinite range B)       Has flat spectral density C)       Has spectral density varying as 1/f D)      Has limited number of frequency components 3.        The depth of penetration of wave in a lossy dielectric increases with increasing A)      Conductivity B)       Permeability C)       Wavelength D)      Permittivity 4.        The intrinsic impedance of copper at high frequencies is A)      Purely resistive B)       Purely inductive C)       Complex with a capacitive component D)      Complex with an inductive component 5.        When electromagnetic waves are propagated in a wave guide A)      They travel alo

Important Multiple Choice Questions in Electrical Circuits 1.        The energy stored in the magnetic field at a solenoid 30 cm long and 3 cm diameter wound with 1000 turns of wire carrying a current at 10A, is A)      0.015 Joule B)       0.15 Joule C)       0.5 Joule D)      1.15 Joule 2.        For a transfer function H(s)= P(s)/Q(s), where P(s) and Q(s) are polynomials in s. Then A)      The degree of P(s) is always greater than the degree of Q(s) B)       The degree of P(s) and  Q(s) are same C)       The degree of P(s) is independent of the  degree of Q(s) D)      The maximum degree of P(s) and  Q(s) differ at most by one 3.        The resistance of a strip of copper of rectangular cross section is 2Ω. A metal of resistivity twice that of copper is coated on its upper surface to a thickness equal to that of copper strip. The resistance of composite strip will be A)      6Ω B)       4/3Ω C)       3/2Ω D)      3/4Ω 4.        The copper armatur

  Important multiple choice questions from Power Electronics 1.       Which one of the following statements is not correct? a)       Power MOSFETs are so constructed as to avoid punch through. b)       In a power MOSFET, the channel length is relatively large and channel width is relatively small c)       Power MOSFETs do not experience any minority carrier storage d)       Power MOSFETs can be put in parallel to handle large currents 2.       Which one is most suitable power device for high frequency (>100 kHz) switching application? a)       Power MOSFET b)       BJT c)       Schottky diode d)       Microwave transistor 3.       A thyristor equivalent of thyratron tube is a)       SCR b)       UJT c)       Diac d)       Triac 4.       Turn-on of thyristor takes place when a)       Anode to cathode voltages is positive b)       Anode to cathode voltages is negative c)       There is a positive current pulse at the gate d)       The