GATE Electrical Engineering Test 4 Question Answers Online

1. Consider a step voltage wave of magnitude 1pu traveling along a lossless transmission line that terminates in a reactor. The voltage magnitude across the reactor at the instant the traveling wave reaches the rector is

2. The Laplace transform of g(t) is

(a)1/s (e³^s – e⁵^s)

(b) 1/s (e⁻⁵^s – e⁻³^s)

(c) e⁻³^s/s (1 – e⁻³^s)

(d) 1/s (e⁵^s – e³^s)

3. For the system 2/(s + 1), the approximate time taken for a step response to reach 98% of its final value is

4. Consider a three-core, there-phase, 50Hz, 11 kV cable whose conductors are denoted as R. Y and B in the figure. The inter-phase capacitance (C1) between each pair of conductors is 0.2 μF and the capacitance between each line conductor and the sheath is 0.4 μF. The per-phase charging current is

5. Figure shows a composite switch consisting of power transistor (BJT) in series with a diode. Assuming that the transistor switch and the diode are ideal, the I-V characteristic of the composite switch is

6. The transistor circuit shown uses a silicon transistor with V_BE = 0.7 V, IC ≈ IE and a dc current again of 100. The value of V₀ is

7. Hair (H), Gita (G), Irfan (I) and Saira (S) are siblings (i.e brothers and sisters). All were born on 1^st January. The age difference between any two successive siblings (that is born one after another) is less than 3 years. Given the following facts.

(I) Hari’s age + Gita age > Irfan’s age + Saira’s age

(II) The4 age difference between Gita and Saira is 1 year. However, Gita is not the oldest and Saira is not the youngest.

(III) There are not twins.

In What order were they born (oldest first)?

8. If the electrical circuit of figure (b) is an equivalent of the coupled tank system of figure (a), then

9. As shown in the figure, a 1Ω resistance is connected across a source that has a load line v + i = 100. The current through the resistance is

10. Choose the most appropriate word from the options given below to complete the following sentence: His rather causal remarks on politics …….. his lack of seriousness about the subject.

11. The second harmonic component of the periodic waveform given in the figure has amplitude of

12. Consider two buses connected by an impedance of (0 + j5)Ω. The bus 1 voltage is 100 ∠30° V, and bus 2 voltage is 100 ∠0° V. The real and reactive power supplied by bus 1, respectively, are

13. A single-phase transformer has a turns ratio of 1 : 2 and is connected to a purely resistive load as shown in the figure. The magnetizing current drawn is 1 A, and the secondary current is 1 A. If core losses and leakage reactance’s are neglected, the primary current is

14. A separately excited DC motor runs at 1500 rpm under no-load with 200 V applied to the armature. The field voltage is maintained at its rated value. The speed of the motor when it delivers a torque of 5 Nm, is 1400 rpm as shown in the figure. The rotational losses and armature reaction are neglected.

The armature resistance of the motor is

15. A minimized form of the function F is

16. The L–C circuit shown in the figure has an inductance L = 1 mH and a capacitance C = 10 μF.

The initial current through the inductor is zero, while the initial capacitor voltage is 100 V. The switch is closed at t = 0. The current I through the circuit is

17. The power electronic converter shown in the figure has a single-pole double-throw switch. The pole P of the switch is connected alternately to throws A and B. The converter shown is a

18. Choose the most appropriate word from the options given below to complete the following sentence: If we manage to …………. Our natural resources, we would leave a better planet for our children.

19. Consider a three-phase, 50 Hz, 11 kV distribution system. Each of the conductors is suspended by an insulator string having two identical porcelain insulators. The self-capacitance of the insulator is 5 times the shunt capacitance between the link and the ground, as shown in the figure. The voltage across the two insulators are

20. An ammeter has a current range of 0-5 A, and its internal resistance is 0.2Ω. In order to change the range to 0 – 25 A, We need to add a resistance of

21. Given digits 2, 2, 3, 3, 4, 4, 4, 4 how many distinct 4 digit numbers greater than 3000 can be formed?

22. A box contains 4 white balls and 3 red balls. In succession, two balls are randomly selected and removed from the box. Given that the first removed ball is white, the probability that the second removed ball is red is

23. Given that the op-amp is ideal, the output voltage V₀ is

24. Consider a stator winding of an alternator with an internal high-resistance ground fault. The currents under the fault condition are as shown in the figure. The winding is protected using a differential current scheme with current transformers of ratio 400/5 A as shown. The current through the operating coil is

25. Assuming that the diodes in the given circuit are ideal, the voltage V₀ is

26. The characteristic equation of a closed-loop system is s(s + 1)(s + 3) + k(s + 2) = 0, k > 0. Which of the following statements is true?

27. Which of the following options is the closest in meaning to the word below:

28. x(t) is a positive rectangular pulse from t = – 1 to t = + 1 with unit height as shown in the figure. The value of ^∞∫_–∞ 1 |X(ω)|² dω {where X(ω) is the Fourier transform of x(t)} is

29. At t = 0, the function f(t) = sin t/t has

30. A three-phase, 33 kV oil circuit breaker is rated 1200 A, 2000 MVA, 3 s. The symmetrical breaking current is

31. A balanced three-phase voltage is applied to a star-connected induction motor, the phase to neutral voltage being V. The stator resistance, rotor resistance referred to the stator, stator leakage reactance, rotor leakage reactance referred to the stator, and the magnetizing reactance are donoted by r_s, r_r, x_s, x_r and X_m, respectively. The magnitude of the starting current of the motor is given by

32. 5 skilled workers can build a wall in 20 days; 8 semi-skilled workers can build a wall in 25 days; 10 unskilled workers can build a wall in 30 days. If a team has 2 skilled, 6 semi-skilled and 5 unskilled workers, how long will it take to build the wall?

33. Given the finite length input x[n] and the corresponding finite length output y[n] of an LTI system as shown below, the impulse response h[n] of the system is

34. The fully controlled thyristor converter in the figure is fed from a single-phase source. When the firing angle is 0°, the de output voltage of the converter is 300 V. What will be the output voltage for a firing angle of 60°, assuming continuous conduction?

35. The switch in the circuit has been closed for a long time. It is opened at t = 0. At t = 0⁺, the current through the 1 μF capacitor is

36. The period of the signal x(t) = 8 sin (0.8πt + π/4) is

37. A balanced star-connected and purely resistive load is connected at the secondary of a star-delta transformer as shown in the figure. The line-to-line voltage rating of the transformer is 110 V/220 V. Neglecting the non-idealities of the transformer, the impedance ‘Z’ of the equivalent star-connected load, referred to the primary side of the transformer, is

38. g(t) can be expressed as

39. A separately excited DC motor runs at 1500 rpm under no-load with 200 V applied to the armature. The field voltage is maintained at its rated value. The speed of the motor when it delivers a torque of 5 Nm, is 1400 rpm as shown in the figure. The rotational losses and armature reaction are neglected.

For the motor to deliver a torque of 2.5 Nm at 1400 rpm, the armature voltage to be applied is

40. Power is transferred from system A to system B by a HVDC link as shown in the figure. If the voltages V_AB and V_CD are as indicated in the figure, and I > 0, then

(a) V_AB < 0, V_CD < 0, V_AB > V_CD

(b) V_AB > 0, V_CD > 0, V_AB < V_CD

(c) V_AB > 0, V_CD > 0, V_AB > V_CD

(d) V_AB > 0, V_CD < 0