Dynamic Braking of DC Shunt Motor MCQ [Free PDF] – Objective Question Answer for Dynamic Braking of DC Shunt Motor Quiz

1. The sine function is an odd function.

A. True
B. False

Answer: A

The odd functions are those functions that are symmetric about the origin. The sine function is an odd function whose time period is 2π.   

 

2. The cosine function is an even function.

A. True
B. False

Answer: A

The even functions are those functions that are a mirror image of the y-axis. The cosine function is an even function whose time period is 2π.   

 

3. Full form of NENO.

A. Neither even nor odd
B. Neither energy nor odd
C. Neither even nor original
D. Neither even nor orthogonal

Answer: A

NENO stands for Neither even nor odd. The functions which are not the mirror image of the y-axis and not symmetric about the origin are NENO functions.   

 

4. The characteristics shown by an element in the V-I curve are V=Is(1-e-V/K). The nature of the element is _______

A. Non-linear, Bilateral, Passive
B. Linear, Unilateral, Active
C. Linear, Bilateral, Passive
D. Non-linear, Unilateral, Passive

Answer: D

The nature of the element is non-linear, unilateral, and passive. The shape of the characteristic is exponential rising. It should be symmetrical in the first and third quadrants for bilateral nature. Its slope is positive in the first quadrant which determines its passive nature.   

 

5. Calculate the resonant frequency if the values of the capacitor and inductor are 2 F and 2 H.

A. .5 rad/sec
B. .6 rad/sec
C. .8 rad/sec
D. .9 rad/sec

Answer: A

During resonance condition XL=Xc. The value of the resonant frequency is

1÷√LC=1÷√4=.5 rad/sec.

The voltage across the capacitor and inductor becomes equal.   

 

6. Calculate the steady-state value for x(t)=7e-9t.

A. 0
B. 8
C. 3
D. 1

Answer: A

The steady-state value is obtained at t=∞.

The value of x(t) at t=∞ is 7e-∞=4(0)=0.

The term e-9t is an exponentially decaying function.   

 

7. The maximum Voltage across the capacitor Vc(t)=Vo(1- e-t) is __________

A. Vo
B. 2Vo
C. 3Vo
D. -Vo

Answer: A

The Vc(t)=Vo(1- e-t) is Vo is the transient equation of the capacitor Voltage.

At the steady-state (t=∞) Vc(t)=Vo(1- e-∞) is Vo.

The maximum voltage across the capacitor is Vo.   

 

8. Calculate the value of the coefficient of coupling for the tightly coupled coils.

A. 0
B. 1
C. 3
D. 2

Answer: B

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

K=M÷√L1.L2.

For tightly coupled coils, the value of the mutual inductance is √L1.L2.

The value of the coefficient of coupling is 1.   

 

9. The maximum current in the inductor IL(t)=Io(1 – e-t/α) is __________

A. Io e-t/α
B. Io
C. 2Io
D. -Io

Answer: B

The IL(t)=Io(1 – e-t/α) is Io is the transient equation of the inductor current.

At the steady-state (t=∞) IL(t)=Io(1- e-∞) is Io.

The maximum current in the inductor is Io.   

 

10. 20 V, 10 A, 10 rpm separately excited dc motor with armature resistance (Ra) equal to .8 ohms. Calculate back emf developed in the motor when it operates on the full load. (Assume rotational losses are neglecteD.

A. 12 V
B. 14 V
C. 13 V
D. 11 V

Answer: A

Back emf developed in the motor can be calculated using the relation

Eb = Vt – I×Ra.

In question, it is asking for a full load. 20 V is terminal Voltage it is fixed so

Eb = 20-10×.8 = 12 V.   

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