Engineering
Engineering MCQs With Answers
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In a 3-phase induction motor, the ratio of rotor copper loss to rotor power input is equal to:
A1 / s
BSlip (s)
C1 - s
Ds^2
The maximum electromagnetic torque developed by a 3-phase induction motor is:
AInversely proportional to rotor resistance
BProportional to square of rotor resistance
CDirectly proportional to rotor resistance
DIndependent of rotor resistance
The total power capacity of two identical single-phase transformers connected in Open-Delta (V-V) configuration is what percentage of a closed delta bank?
A66.7%
B57.7%
C86.6%
D50.0%
The saving of copper in an auto-transformer compared to a conventional two-winding transformer with transformation ratio K (V2/V1 < 1) is proportional to:
A1 / K
BK
CK^2
D1 - K
Eddy current loss in transformer cores is minimized by:
AIncreasing supply current
BUsing thin laminated sheets insulated with varnish
CUsing solid cast iron cores
DIncreasing core thickness
Silicon steel is chosen for core construction in electrical machines because it offers:
AHigh electrical conductivity
BHigh mechanical copper strength
CLow resistance to eddy currents
DLow hysteresis loss and high magnetic permeability
The hysteresis loop area of a ferromagnetic material represents:
ATotal magnetic flux density
BPermeability of material
CEnergy loss per unit volume per cycle
DCoercive force required
Lenz’s Law in electromagnetic induction directly complies with which conservation law?
ALaw of Conservation of Mass
BLaw of Conservation of Charge
CLaw of Conservation of Momentum
DLaw of Conservation of Energy
Kelvin’s Double Bridge is designed to eliminate lead and contact resistances when measuring:
AMedium resistances
BVery low resistances (< 1 ohm)
CInductive reactances
DHigh insulation resistances
In a 3-phase delta-connected balanced load, the line current I_L is equal to:
A3 * I_ph
Bsqrt(3) * I_ph
CI_ph / sqrt(3)
DI_ph