Regenerative Braking of Induction Motor MCQ [Free PDF] – Objective Question Answer for Regenerative Braking of Induction Motor Quiz

51. Calculate the value of the coefficient of coupling for the isolated coils.

A. 0
B. 1
C. 5
D. 7

Answer: A

The coefficient of coupling expresses how the two coils are magnetically coupled. It is mathematically represented as

K=M÷√L1.L2.

For the isolated coils, the value of the mutual inductance is 0. The value of the coefficient of coupling is 0.   

 

52. Calculate the value of equivalent inductance for series aiding of two coils whose self inductances are 5 H, 2 H, and mutual inductance value

is 4 H.
A. 15 H
B. 12 H
C. 13 H
D. 11 H

Answer: A

The equivalent inductance for series aiding of two coils is

Leq=L1+L2+2M=5+2+8=15 H.

The value of equivalent inductance increases due to mutually induced e.m.f in the case of the magnetically coupled circuit.   

 

53. Calculate the value of equivalent inductance for series subtracting polarity of two coils whose self inductances are 14 H, 5 H, and mutual inductance value is 1 H.   [/bg_collapse]

A. 15 H
B. 17 H
C. 12 H
D. 10 H

Answer: B

The equivalent inductance for series subtracting of two coils is

Leq=L1+L2-2M=14+5-2=17 H.

The value of equivalent inductance decreases due to negatively mutually induced e.m.f in the case of the magnetically coupled circuit.   

 

54. Calculate the value of the capacitive reactance during resonance if the value of the inductor is 5 H and the supply frequency is 20 rad/sec.

A. 100 Ω
B. 200 Ω
C. 300 Ω
D. 700 Ω

Answer: A

Resonance is defined as the phenomenon in which the energy of any element changes from one form to another. During resonance condition

Xc=Xl=ΩL=20×5=100 Ω.   

 

55. Calculate the quality factor for the R-L circuit if R=28 Ω and L=2 H.

A. 14
B. 16
C. 10
D. 17

Answer: A

The quality factor is defined as the ratio of the reactive power to the active power consumed. The resistor always absorbs active power and the inductor absorbs the reactive power.

Quality factor=R÷L=28÷2=14.   

 

56. The quality factor is calculated for ___________

A. Power factor loads
B. Inductive coils
C. Lagging loads
D. Leading loads

Answer: B

The quality factor is calculated for inductive coils, not for power factor loads. Its value determines the quality of the inductor or capacitor. It shows how good an inductor or capacitor can absorb reactive power.   

 

57. Calculate the equivalent resistance when two resistances are connected in parallel of values 8 Ω, and 8 Ω.

A. 3 Ω
B. 2 Ω
C. 4 Ω
D. 7 Ω

Answer: C

When two resistances are connected in parallel their equivalent resistance is equal to the harmonic mean of the individual resistances.

Req=R1.R2÷(R1+R2)=8×8÷(8+8)=4 Ω.   

 

58. Calculate the quality factor for the R-C circuit if R=2 Ω and C=1 F.

A. 0.2
B. 0.4
C. 0.6
D. 0.5

Answer: D

The quality factor is defined as the ratio of the reactive power to the active power consumed. The resistor always absorbs active power and the capacitor absorbs the reactive power.

Quality factor=1÷RC=1÷2=.5.   

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