Electrical Engineering GATE 2018 Questions with Answer

Ques 27 Electrical Circuits

The voltage across the circuit in the figure, and the current through it, are given by the following expressions:

If the average power delivered to the circuit is zero, then the value of X (in Ampere) is _____ (up to 2 decimal places).

10.00 is the correct answer.

Ques 28 Electrical Circuits

The voltage v(t) across the terminals a and b as shown in the figure, is a sinusoidal voltage having a frequency ω = 100 radian/s. [cite: 118, 119] When the inductor current i(t) is in phase with the voltage v(t), the magnitude of the impedance Z (in Ω) seen between the terminals a and b is ________ (up to 2 decimal places).

50.00 is the correct answer.

Ques 29 Electrical Machine

A single-phase 100 kVA, 1000 V / 100 V, 50 Hz transformer has a voltage drop of 5% across its series impedance at full load. Of this, 3% is due to resistance. The percentage regulation of the transformer at full load with 0.8 lagging power factor is

4.8

6.8

8.8

10.8

Ques 30 Electrical Machine

In a salient pole synchronous motor, the developed reluctance torque attains the maximum value when the load angle in electrical degrees is

Ques 31 Electrical Machines

A separately excited dc motor has an armature resistance R_a=0.05 Ω. The field excitation is kept constant. At an armature voltage of 100 V, the motor produces a torque of 500 Nm at zero speed. Neglecting all mechanical losses, the no-load speed of the motor (in radian/s) for an armature voltage of 150 V is ________ (up to 2 decimal places).

600 is the correct answer.

Ques 32 Electrical Machines

A transformer with toroidal core of permeability $\mu$ is shown in the figure. Assuming uniform flux density across the circular core cross-section of radius $r<

^μV_{r²N_P²ω}/I

^{μIr²N_pN_Sω}/V

^{μVr²N_P²ω}/2I

^{μIr²N_P²ω}/2V

Ques 33 Electrical Machines

A 3-phase 900 kVA, 3 kV / (3 / √3) kV (∆/Y), 50 Hz transformer has primary (high voltage side) resistance per phase of 0.3 Ω and secondary (low voltage side) resistance per phase of 0.02 Ω. [cite: 107] Iron loss of the transformer is 10 kW. The full load % efficiency of the transformer operated at unity power factor is _______ (up to 2 decimal places).

97.20 is the correct answer.

Ques 34 Electrical Machines

A 200 V DC series motor, when operating from rated voltage while driving a certain load, draws 10 A current and runs at 1000 r.p.m. [cite: 109] The total series resistance is 1 $\Omega$. [cite: 110] The magnetic circuit is assumed to be linear. [cite: 111] At the same supply voltage, the load torque is increased by 44%. The speed of the motor in r.p.m. [cite: 111, 112] (rounded to the nearest integer) is ________ .

825 is the correct answer.

Ques 35 Electrical Machines

The equivalent circuit of a single phase induction motor is shown in the figure, where the parameters are X_l1 = X_l2 = 2 Ω, R₁ = R₂ = 2 Ω, X_M = 240 Ω and s is the slip. [cite: 115] At no-load, the motor speed can be approximated to be the synchronous speed. [cite: 116, 117] The no-load lagging power factor of the motor is___________ (up to 3 decimal places).

0.105 is the correct answer.

Ques 36 Electromagnetics

A positive charge of 1 nC is placed at (0, 0, 0.2) where all dimensions are in metres. Consider the x-y plane to be a conducting ground plane. Take ε₀ = 8.85 × 10^-12 F/m. The Z component of the E field at (0, 0, 0.1) is closest to

899.18 V/m

-899.18 V/m

999.09 V/m

-999.09 V/m

Ques 37 Electromagnetics

The capacitance of an air-filled parallel-plate capacitor is 60 pF. When a dielectric slab whose thickness is half the distance between the plates, is placed on one of the plates covering it entirely, the capacitance becomes 86 pF. Neglecting the fringing effects, the relative permittivity of the dielectric is _____________ (up to 2 decimal places).

2.53 is the correct answer.

Ques 38 Engineering Mathematics

Let f be a real-valued function of a real variable defined as f(x) = x² for x ≥ 0, and f(x) = -x² for x < 0. Which one of the following statements is true?

f(x) is discontinuous at x=0.

f(x) is continuous but not differentiable at x=0.

f(x) is differentiable but its first derivative is not continuous at x=0

f(x) is differentiable but its first derivative is not differentiable at x=0.

Ques 39 Engineering Mathematics

The value of the directional derivative of the function Φ(x, y, z) = x y² + y z² + z x² at the point (2, -1, 1) in the direction of the vector p = i + 2j + 2k is

0.95

0.93

0.9

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Electrical Engineering GATE 2018 Questions with Answer