Engineering
Engineering MCQs With Answers
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A Cycloconverter is a power electronic circuit used to convert:
ADC power into high frequency AC
BAC power at one frequency directly into AC power at another frequency
CFixed DC into variable DC
DAC power into DC power
In a two-wattmeter method for 3-phase power measurement, one wattmeter reads zero when the load power factor angle is:
A60 degrees (cos phi = 0.5)
B0 degrees (cos phi = 1.0)
C90 degrees (cos phi = 0.0)
D30 degrees (cos phi = 0.866)
The Latching Current of an SCR is always:
AGreater than its Holding Current
BLess than its Holding Current
CEqual to its Holding Current
DZero
The total active power P in a balanced 3-phase system expressed in terms of line voltage V_L and line current I_L is:
A3 * V_L * I_L * cos(phi)
Bsqrt(3) * V_L * I_L * cos(phi)
Csqrt(3) * V_L * I_L * sin(phi)
DV_L * I_L * cos(phi)
When measuring power in a 3-phase 3-wire system using the two-wattmeter method, both wattmeters read equal positive values when load power factor is:
AUnity (1.0)
BZero
C0.866 leading
D0.5 lagging
The active power consumed by a pure inductor connected across an AC voltage source is:
AV * I Watts
BZero Watts
CI^2 * X_L Watts
DV^2 / X_L Watts
The RMS value of a pure sinusoidal voltage wave with peak value V_m is:
AV_m / 2
BV_m / pi
CV_m / sqrt(2)
D2 * V_m / pi
For a closed-loop control system to be stable, both Gain Margin (GM) and Phase Margin (PM) expressed in dB and degrees must be:
AEqual to infinity
BZero
CNegative
DPositive
In Norton’s equivalent circuit, the equivalent current source I_N is determined by finding the:
AShort-circuit current between output terminals
BCurrent flowing when supply voltage is zero
COpen-circuit voltage between output terminals
DMaximum load current under unity power factor
In Routh-Hurwitz stability criterion, the number of roots of the characteristic equation lying in the right half of the s-plane equals:
ANumber of sign changes in the first column of Routh array
BNumber of zero elements in second column
CNumber of rows in Routh array
DTotal degree of characteristic polynomial plus one