Solved Question preview paper (2) 1-50

Q.1. By looking at which part of the motor it can be easily confirmed that a particular motor is DC motor
a.)Frame
b.) Shaft
c.) Commutator✔
d.) Stator

Q.2. In regenerative braking which of the following is true
a.) Motor energy is dissipated as heat
b.) Motor energy is dissipated in armature heating
c.) Motor energy is dissipated in voltage loss
d.) Motor is mode to run as generator✔

Q.3. Which of the following load normally needs starting torque more than rated torque
a.) Blower
b.) Conveyors✔
c.) Air compressor
d.) Centrifugal pump

Q.4. Which of the following is not a vector quantity
a.) Linear momentum
b.) Angular momentum
c.) Electric field
d.) Electric potential✔

Q.5. Magnetic moment is a
a.) Pole strength
b.) Universal constant
c.) Scalar quantity
d.) Vector quantity✔

Q.6. Auto transformer makes affecting savings on Copper and copper losses when its Transformer ratio is equal to
a.) Approximate one✔
b.) Less than 1
c.) Greater than 1
d.) None of the above

Q.7. In circle diagram of induction motor diameter of circle represents which of the following
a.) Slip
b.) Rotor current✔
c.) Running torque
d.) Line voltage

Q.8. Inside a hollow conducting sphere
a.) Electric field is zero✔
b.) Electric field is a non zero constant
c.) Electric field changes with magnitude of the charge given to the conductor
d.) Electric field changes with distance from the centre of sphere

Q.9. To infinite parallel metal plates are charged with equal surface charge density of the same polarity. The electric field in the gap between the plate is
a.) Same as the product by 1 plate
b.) Double the field produced by 1 plate
c.) Depend on coordinates of field plate
d.) Zero✔

Q.10. The chemical effect of current is used in
a.) DC ampere hour meter✔
b.) DC ammeter
c.) DC energy meter
d.) None of the above

Q.11. Permittivity of free spare is equal to
a.) 8.854×10 - 8 F/m
b.) 8. 84× 10-12F/m✔
c.) 9×10-9 F/m
d.) 6×10 -12F/m

Q.12. Swamping resistance is used to compensate
a.) Error due to temperature variation✔
b.) Compensate error due to strong magnetic field
c.) Both A and B
d.) None of these

Q.13. 25kV, 50Hz 1phase supply is used for supplying power to the locomotives throughout India except which zone ?
a.) West✔
b.) East
c.)South
d.) North East

Q.14. Unit of deflection sensitivity of a CRO is
a.) V /mm
b.) Meter/ volt✔
c.) mm per mV
d.) mm /v

Q.15. ALNICO  is an alloy of
a.) Iron ,aluminium
b.) Aluminium ,Nickel
c.) Iron ,Cobalt, Nickel✔
d.) Aluminium ,nickel, iron and Cobalt

Q.16. Three resistors each of R ohms connected to form a triangle. the resistance between any two terminals will be
a.)3/2R
b.)2/3R✔
c.)P/2
d.)3R

Q.17. Air core Transformer as compared to iron core Transformer has
a.) More copper loss
b.) Less magnetic core loss
c.) More magnetic core loss
d. No magnetic core loss✔

Q.18. choose the best suitable of diamagnetic :paramagnetic material
a.) water :air✔
b.) Iron : steel
c.) Permalloy : super alloys
d.) Nickel : Cobalt

Q.19 find the odd one out
a.) Absorptivity
b.) Emissivity
c.) Refractive index
d.) Dielectric strength✔

Q.20. Grounded wire is used to
a.) To give sport to Towers
b.) Give a good regulations
c.) Increase conductivity of wire
d.) Connect a circuit conductor to an Earth plate✔

Q.21. Which of the following has approx zero temperature coefficient of resistance
a.)Manganin✔
b.) Carbon
c.) Porcelain
d.) copper

Q.22. Siemens are unit of
a.) Resistance
b.) conductance✔
c.) Capacitance
d.) Impedance

Q.23. If 220 volt heater is used on 110 volt supply heat produced will be
a.) Half Times
b.) 2 times
c.) One fourth✔
d.) 4 times

Q.24. If 5 resistance of 50 ohms are connected in parallel then unitor resistance will be
a.)1Ω
b.)10Ω✔
c.)100Ω
d.)250Ω

Q.25. If four resistance of 50 ohms each are connected in series across 250 volts supply and 1 resistance become open circuit then voltage across that register will be
a.) 0
b.)infinite✔
c.)250volts
d.)Any value

Q.26. In a three phase balanced load the power consumed is given by
a.)3VLILcosΦ
b.)√3VL IL cosΦ✔
c.)√3Vph Iph cosΦ
d.)VL IL cosΦ

Q.27. When two wattmeter are used to measure Pawar of three phase balanced circuit and one wattmeter reads negative ,it means power factor of load is
a.) Zero
b.) More the 0.5
c.)Less then 0.5
d.) 1✔

Q.28. 3 identical resistors each of 15 ohm are connected in Star connection across 400 volts three phase supply the value of resistance on each face of equivalent Delta will be
a.)5Ω
b.)45Ω✔
c.)50Ω
d.)75Ω

Q.29. Two coils connected in parallel across 100 volt supply mains take 10 ampere from the line the power dissipated in one coil is 600 watt what is the resistance of other coil
a.)5Ω
b.)15Ω
c.)25Ω✔
d.)35Ω

Q.30. Superposition theorem is essentially based on the concept of
a.) Duality
b.) Linearity✔
c.) Reciprocity
d.) Non linearity

Q.31. Torque of a single phase induction motor at synchronous speed is
a.) Zero
b.) Negative✔
c.) Positive
d.) Multiple

Q.32. Starting torque of an induction motor is proportional to
a.)1/2 supply voltage
b.)(supply voltage)1/2
c.)(supply voltage)
d.)(supply voltage)2✔

Q.33. An induction motor is in general is analogous to
a.) an auto transformer
b.) A two winding Transformer with its secondary open circuit
c.)  A two winding transformer with seconds short circuit✔
d.) A three winding transformer

Q.34. The slip of induction motor under full load is about
a.)0.1
b.)0.2
c.)0.3✔
d.)0.8

Q.35. The rated speed of an induction motor is 1410 RPM what is meant by the statement "the sleep' =1?
a.) The motor runs at synchronous speed
b.) Motor runs at rated speed
c.) Speed is high then synchronous speed
d.) Rotor is stationary✔

Q.36 If the auto transformer tapping 'K' is less than 1 starting torque of squirrel cage induction motor with the Transformer starter is
a.) K time starting torque
b.) K2 time starting torque✔
c.) 1/2 Time starting torque
d.)1/K2Time starting torque

Q.37 the direction of rotation of shaded pole motor is always toward the
a.) Main pole
b.) Shaded pole✔
c.) Salient pole
d.) Consequent

Q.38. Overload protection in Emmanuelle starting switch is provided by
a.) Dual element fuse
b.) Toggle switch
c.) Thermal activated device✔
d.) Snap action mechanism

Q.39. Single phase induction motor can be brought off as a composite of two motor mechanically coupled if one of these motor has slip 'S' then sleep of other motor is
a.)S
b.)(1-S)
c.)(2-S)✔
d.)0.55

Q.40. Single phase Universal motor can run on
a.)A.C.supply
b.)DC supply
c.) Both A and B✔
d.)Rectified DC only

Q.41. Hi speed alternator are driven by
a.) Diesel engine
b.) Steam turbines✔
c.) Hydraulic turbines
d.)None

Q.42. Carbon brushes are used in a DC machine because
a.) Karbonn lubricates and polishes the commutator✔
b.) Contact resistance is decreased
c.) Carbon is cheap
d.) Carbon is abundant

Q.43. Which motor has the best speed regulation
a.) Series
b.) Shunt
c.) Commutativity compound✔
d.) Differentially compound

Q.44. A comparatively  compound motor does not run at dangerous speed at light load because of the presence of
a.) Shunt winding✔
b.) Interpoles
c.) Series
d.) Compensating winding

Q.45 the AC armature winding of an alternator is
a.) Always star connected✔
b.) Star delta connected
c.) Generally Delta connected
d.) Pi connected

Q.46. Damper winding are used in alternator to
a.) Prevent hunting✔
b.) Achieve synchronism
c.) Reduce find age loss
d.) Reduce Eddy current loss

Q47. What can be found in a transformer with open circuit test
a.) Copper losses
b.) Turn ratio✔
c.) Total equivalent resistance
d.) Total equivalent leakage resistance

Q.48. The efficiency of a transformer will be at maximum when
a.) Leakage reactance of the two winding are equal
b.) Resistance of the two winding are equal
c.) Copper loss is equal to constant loss✔
d.) Copper loss is zero

Q.49. Combination of AC motor DC generator and exciter to provide adjustable voltage DC power to a DC motor
a.) Ward-Leonard system✔
b.) Half wave SCR adjustable voltage supply
c.) Compound motor
d.) Universal motor

Q.50. A series motor will over speed when
a.) The load is increased
b.) The armature circuit is open
c.) The field ID opened
d.) Load is removed✔