Electrical Engineering
Electrical Engineering MCQs with Answers
Electrical engineering MCQs with answers and detailed explanations for PEC, NTS, WAPDA and engineering job tests. Machines, circuits and power systems. Take a scored quiz instead →
According to the Nyquist-Shannon sampling theorem, to prevent aliasing, the minimum sampling rate f_s must be:
AAt least twice the maximum message frequency (2 * f_max)
BHalf of the maximum message frequency (0.5 * f_max)
CEqual to the maximum message frequency (f_max)
DFour times the maximum message frequency (4 * f_max)
Pitch factor (or chord factor) K_p of an alternator coil short-pitched by angle alpha is equal to:
Asin(alpha / 2)
Bcos(alpha / 2)
Ctan(alpha / 2)
Dcos(alpha)
A two-port linear network is classified as reciprocal if its Z-parameters satisfy which condition?
AZ11 = Z22
BZ11 * Z22 = Z12 * Z21
CZ12 = -Z21
DZ12 = Z21
A two-port linear network is defined as symmetrical if its ABCD transmission parameters satisfy:
AAD - BC = 1
BA = D
CB = C
DA = B
In a Boost converter (step-up DC-DC chopper), the average output voltage V_o is given by:
AV_o = D * V_s
BV_o = D * V_s / (1 - D)
CV_o = V_s / (1 - D)
DV_o = (1 - D) * V_s
What is the primary role of a freewheeling diode connected across an inductive load in a converter circuit?
AIncreases supply current
BReverses direction of load current
CDissipates stored magnetic energy and prevents inductive voltage spikes
DReduces output DC voltage
In a Buck converter (step-down DC-DC chopper), the average output voltage V_o in terms of input voltage V_s and duty cycle D is:
AV_o = D * V_s
BV_o = V_s / (1 - D)
CV_o = V_s / D
DV_o = D * V_s / (1 - D)
A TRIAC can be simplified as being equivalent to:
ATwo SCRs connected in anti-parallel with a common gate
BAn SCR and a diode in series
CTwo BJTs connected back-to-back
DTwo diodes in series
A Semiconductor Controlled Rectifier (SCR) is a solid-state device containing how many PN junctions?
A4 PN junctions
B3 PN junctions
C1 PN junction
D2 PN junctions
A Mho relay (admittance relay) is inherently directional and is best suited for protecting:
ADistribution transformers
BShort transmission lines
CLong transmission lines
DMedium length transmission lines