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 →
The Thermal Runaway phenomenon in a BJT amplifier is primarily caused by:
ABreakdown of emitter insulation
BBase width modulation
CExcessive gate voltage applied to collector
DUncontrolled cumulative increase in collector current due to temperature rise
An ideal operational amplifier has input impedance R_in and output impedance R_out equal to:
AR_in = infinity, R_out = 0
BR_in = infinity, R_out = infinity
CR_in = 0, R_out = infinity
DR_in = 100 kOhm, R_out = 50 Ohm
The ripple factor of a full-wave bridge rectifier without filter circuit is equal to:
A0.707
B1.21
C0.406
D0.482
Which semiconductor device exhibits negative differential resistance region in its I-V characteristics?
AVaractor Diode
BTunnel Diode
CZener Diode
DSchottky Diode
The surge impedance of an underground power cable is approximately:
A400 Ohms to 500 Ohms
B4000 Ohms
C5 Ohms
D40 Ohms to 50 Ohms
A p-n junction diode under reverse bias condition has a depletion region width that:
ABecomes zero
BDecreases
CRemains constant
DIncreases
Arc extinction in a High Voltage AC Circuit Breaker is achieved by:
AApplying DC reverse voltage
BIncreasing arc resistance to infinity instantly
CIncreasing dielectric strength of the medium between contacts
DShorting the contacts permanently
A symmetrical 3-phase fault on a power transmission system is characterized by:
AEqual fault currents in all three phases spaced 120 degrees apart
BUnbalanced phase voltages
CHigh zero-sequence current flow
DDominant negative-sequence components
The standard per-unit impedance Z_pu of a system component on new base quantities is calculated using:
AZ_pu(new) = Z_pu(old) * (MVA_old / MVA_new)^2
BZ_pu(new) = Z_pu(old) * (kV_old / kV_new)^2 * (MVA_new / MVA_old)
CZ_pu(new) = Z_pu(old) * (kV_new / kV_old)^2 * (MVA_new / MVA_old)
DZ_pu(new) = Z_pu(old) * (kV_new / kV_old) * (MVA_old / MVA_new)
Corona loss in an overhead transmission line increases significantly during:
ALow voltage operation
BHot dry summer days
CStormy and humid weather
DSmooth conductor surface conditions