Important Paper NDA

1. Shunt reactors are sometimes used in high voltage transmission system to
(a) limit the short circuit current through the line
(b) compensate for the series reactance of the line under heavily loaded condition
(c) limit over voltage at the load side under lightly loaded condition
(d) compensate for the voltage drop in the line under heavily loaded condition
Ans. (c)
2. Which of the following is an invalid state in an 8-4-2-1 binary codede decimal counter
(a) 1000
(b) 1001
(c) 0011
(d) 1100
Ans. (a)
3. In a synchronous machine, hunting is predominantly damped by
(a) mechanical losses in the rotor
(b) iron losses in the rotor
(c) copper losses in the stator
(d) copper losses in the rotor
Ans. (d)
4. For a fully transposed transmission line
(a) positive negative and zero sequence impedances are equal
(b) positive and negative sequence impedances are equal
(c) zero and positive sequence impedances are equal
(d) negative and zero sequence impedances are equal                                       
Ans. (b)
5. A non-ideal voltage source Vs has an internal impedance of Zs. If a purely resistive load is to be chosen that maximises the power transferred to the load, its value must be
(a) 0
(b) real part of Zs
(c) magnitude of Zs
(d) complex conjugate of Zs
Ans. (d)
6. For a single-phase two winding transformer, the supply frequency and voltage are both increased by 10%. The percentage changes in the hystresis loss and eddy current loss, respectively are
(a) 10 and 21
(b) -10 and 21
(c) 21 and 10
(d) -21 and 10
Ans. (a)
7. Suppose the resistors R1 and R2 are connected in parallel to give an equivalent resistor R. if resistors R1 and R2 have tolerance of 1% each, the equivalent resistor R for resistors R1 = 300 Ω and R2 = 200Ω will have tolerance of
(a) 0.5%
(b) 1%
(c) 1.2%
(d) 2%
Ans. (b)
8. Even he worked hard, he failed in the examination.
a. since
b. Although
c. For
d. No improvement
ans  (b)
9. He was asked to arbitrate with two merchants in a dispute.
a.to arbitrate between
b. to arbitrate at
c. to arbitrate
d. No improvement
ans (a)
10. He is definitely the cleverer among the toe .
a. in
b. of
c. than
d. No improvement
ans (b)

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