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GATE EE 2018 Set 1

All 65 solved GATE EE 2018 Set 1 questions in exam order. Open a question, commit to an answer, and learn from the step-by-step solution. One question at a time.

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Questions

65

Paper marks

100

Question formats

2

MCQ · NAT

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Self-paced

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Difficulty mixEasy 17Medium 43Hard 5

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65 of 65 questions

General Aptitude (GA)

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    Question

    “Since you have gone off the ______, the _______ sand is likely to damage the car.”
    The words that best fill the blanks in the above sentence are
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    Question

    “A common misconception among writers is that sentence structure mirrors thought; the more _________ the structure, the more complicated the ideas.”
    The word that best fills the blank in the above sentence is
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    Question

    The three roots of the equation f(x)=0f(x) = 0 are x={2,0,3}x = \{-2, 0, 3\}. What are the three values of xx for which f(x3)=0f(x - 3) = 0?
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    Question

    For what values of k given below is (k+2)2k3\frac{(k+2)^2}{k-3} an integer?
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    Question

    Functions F(a,b)F(a, b) and G(a,b)G(a, b) are defined as follows:
    F(a,b)=(ab)2F(a, b) = (a - b)^2 and G(a,b)=abG(a, b) = |a - b|, where x|x| represents the absolute value of xx.
    What would be the value of G(F(1,3),G(1,3))G(F(1, 3), G(1, 3))?
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    Question

    An e-mail password must contain three characters. The password has to contain one numeral from 0 to 9, one upper case and one lower case character from the English alphabet. How many distinct passwords are possible?
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    Question

    In a certain code, AMCF is written as EQGJ and NKUF is written as ROYJ. How will DHLP be written in that code?
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    Question

    A class of twelve children has two more boys than girls. A group of three children are randomly picked from this class to accompany the teacher on a field trip. What is the probability that the group accompanying the teacher contains more girls than boys?
    1. A.
      0
    2. B.
      325864\frac{325}{864}
    3. C.
      525864\frac{525}{864}
    4. D.
      512\frac{5}{12}

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    Question

    A designer uses marbles of four different colours for his designs. The cost of each marble is the same, irrespective of the colour. The table below shows the percentage of marbles of each colour used in the current design. The cost of each marble increased by 25%. Therefore, the designer decided to reduce equal numbers of marbles of each colour to keep the total cost unchanged. What is the percentage of blue marbles in the new design?
    BlueBlackRedYellow
    40%25%20%15%
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    Question

    P, Q, R and S crossed a lake in a boat that can hold a maximum of two persons, with only one set of oars. The following additional facts are available.
    (i) The boat held two persons on each of the three forward trips across the lake and one person on each of the two return trips.
    (ii) P is unable to row when someone else is in the boat.
    (iii) Q is unable to row with anyone else except R.
    (iv) Each person rowed for at least one trip.
    (v) Only one person can row during a trip.
    Who rowed twice?
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ELECTRICAL ENGINEERING

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    Question

    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
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    Question

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

    A single phase fully controlled rectifier is supplying a load with an anti-parallel diode as shown in the figure. All switches and diodes are ideal. Which one of the following is true for instantaneous load voltage and current?

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    Question

    Four power semiconductor devices are shown in the figure along with their relevant terminals. The device(s) that can carry dc current continuously in the direction shown when gated appropriately is (are)
    Four power semiconductor devices: Thyristor, Triac, GTO, and MOSFET with current directions shown.
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    Question

    Two wattmeter method is used for measurement of power in a balanced three-phase load supplied from a balanced three-phase system. If one of the wattmeters reads half of the other (both positive), then the power factor of the load is
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    Question

    Consider a lossy transmission line with V1V_1 and V2V_2 as the sending and receiving end voltages, respectively. ZZ and XX are the series impedance and reactance of the line, respectively. The steady-state stability limit for the transmission line will be
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    Question

    The graph of a network has 8 nodes and 5 independent loops. The number of branches of the graph is
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    Question

    In the figure, the voltages are v1(t)=100cos(ωt)v_1(t) = 100\cos(\omega t), v2(t)=100cos(ωt+π/18)v_2(t) = 100\cos(\omega t + \pi/18) and v3(t)=100cos(ωt+π/36)v_3(t) = 100\cos(\omega t + \pi/36). The circuit is in sinusoidal steady state, and RωLR \ll \omega L. P1P_1, P2P_2 and P3P_3 are the average power outputs. Which one of the following statements is true?

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    Question

    Match the transfer functions of the second-order systems with the nature of the systems given below.
    Transfer functionsNature of system
    P: 15s2+5s+15\frac{15}{s^2 + 5s + 15}I: Overdamped
    Q: 25s2+10s+25\frac{25}{s^2 + 10s + 25}II: Critically damped
    R: 35s2+18s+35\frac{35}{s^2 + 18s + 35}III: Underdamped
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    Question

    A positive charge of 11 nC is placed at (0,0,0.2)(0, 0, 0.2) where all dimensions are in metres. Consider the xyx - y plane to be a conducting ground plane. Take ϵ0=8.85×1012\epsilon_0 = 8.85 \times 10^{-12} F/m. The zz component of the E field at (0,0,0.1)(0, 0, 0.1) is closest to
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    Question

    Let ff be a real-valued function of a real variable defined as f(x)=x2f(x) = x^2 for x0x \geq 0, and f(x)=x2f(x) = -x^2 for x<0x < 0. Which one of the following statements is true?
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    Question

    The value of the directional derivative of the function Φ(x,y,z)=xy2+yz2+zx2\Phi(x, y, z) = xy^2 + yz^2 + zx^2 at the point (2, -1, 1) in the direction of the vector p=i+2j+2k\mathbf{p} = \mathbf{i} + 2\mathbf{j} + 2\mathbf{k} is
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    Question

    The value of the integral Cz+1z24dz\oint_C \frac{z+1}{z^2-4} dz in counter clockwise direction around a circle C of radius 1 with center at the point z = -2 is
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    Question

    In the logic circuit shown in the figure, Y is given by

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    Question

    The op-amp shown in the figure is ideal. The input impedance viniin\frac{v_{in}}{i_{in}} is given by

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    Question

    A continuous-time input signal x(t)x(t) is an eigenfunction of an LTI system, if the output is
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    Question

    Consider a non-singular 2×22 \times 2 square matrix A. If trace(A)=4trace(\mathbf{A}) = 4 and trace(A2)=5trace(\mathbf{A}^2) = 5, the determinant of the matrix A is _________(up to 1 decimal place).
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    Question

    Let ff be a real-valued function of a real variable defined as f(x)=x[x]f(x) = x - [x], where [x][x] denotes the largest integer less than or equal to xx. The value of 0.251.25f(x)dx\int_{0.25}^{1.25} f(x) dx is _______ (up to 2 decimal places).
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    Question

    In the two-port network shown, the h11h_{11} parameter (where, h11=V1I1, when V2=0)\left( \text{where, } h_{11} = \frac{V_1}{I_1}, \text{ when } V_2 = 0 \right) in ohms is _____________ (up to 2 decimal places).

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    Question

    The series impedance matrix of a short three-phase transmission line in phase coordinates isZabc=[ZsZmZmZmZsZmZmZmZs]Z_{abc} = \begin{bmatrix} Z_s & Z_m & Z_m \\ Z_m & Z_s & Z_m \\ Z_m & Z_m & Z_s \end{bmatrix}If the positive sequence impedance is (1+j10)Ω(1 + j10) \Omega, and the zero sequence is (4+j31)Ω(4 + j31) \Omega, then the imaginary part of ZmZ_m (in Ω\Omega) is __________ (up to 2 decimal places).
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    Question

    The positive, negative and zero sequence impedances of a 125 MVA, three-phase, 15.5 kV, star-grounded, 50 Hz generator are j0.1j0.1 pu, j0.05j0.05 pu and j0.01j0.01 pu respectively on the machine rating base. The machine is unloaded and working at the rated terminal voltage. If the grounding impedance of the generator is j0.01j0.01 pu, then the magnitude of fault current for a b-phase to ground fault (in kA) is __________ (up to 2 decimal places).
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    Question

    A 1000×10001000 \times 1000 bus admittance matrix for an electric power system has 80008000 non-zero elements. The minimum number of branches (transmission lines and transformers) in this system are _____ (up to 2 decimal places).
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    Question

    The waveform of the current drawn by a semi-converter from a sinusoidal AC voltage source is shown in the figure. If I0=20I_0 = 20 A, the rms value of fundamental component of the current is ___________A (up to 2 decimal places).
    Waveform of current drawn by a semi-converter showing current $I_0$ from $30^\circ$ to $180^\circ$ and $-I_0$ from $210^\circ$ to $360^\circ$
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    Question

    A separately excited dc motor has an armature resistance Ra=0.05 ΩR_a = 0.05\text{ }\Omega. The field excitation is kept constant. At an armature voltage of 100 V100\text{ V}, the motor produces a torque of 500 Nm500\text{ Nm} at zero speed. Neglecting all mechanical losses, the no-load speed of the motor (in radian/s) for an armature voltage of 150 V150\text{ V} is _____ (up to 2 decimal places).
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    Question

    Consider a unity feedback system with forward transfer function given byG(s)=1(s+1)(s+2)G(s) = \frac{1}{(s+1)(s+2)}The steady-state error in the output of the system for a unit-step input is _________(up to 2 decimal places).
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    Question

    A transformer with toroidal core of permeability μ\mu is shown in the figure. Assuming uniform flux density across the circular core cross-section of radius rRr \ll R, and neglecting any leakage flux, the best estimate for the mean radius RR is

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    Question

    A 0-1 Ampere moving iron ammeter has an internal resistance of 50 mΩ50\text{ m}\Omega and inductance of 0.1 mH0.1\text{ mH}. A shunt coil is connected to extend its range to 0-10 Ampere for all operating frequencies. The time constant in milliseconds and resistance in mΩ\text{m}\Omega of the shunt coil respectively are
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    Question

    The positive, negative and zero sequence impedances of a three phase generator are Z1,Z2Z_1, Z_2 and Z0Z_0 respectively. For a line-to-line fault with fault impedance ZfZ_f, the fault current is If1=kIfI_{f1} = k I_f, where IfI_f is the fault current with zero fault impedance. The relation between ZfZ_f and kk is
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    Question

    Consider the two bus power system network with given loads as shown in the figure. All the values shown in the figure are in per unit. The reactive power supplied by generator G1G_1 and G2G_2 are QG1Q_{G1} and QG2Q_{G2} respectively. The per unit values of QG1,QG2Q_{G1}, Q_{G2}, and line reactive power loss (QlossQ_{loss}) respectively are

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    Question

    The per-unit power output of a salient-pole generator which is connected to an infinite bus, is given by the expression, P=1.4sinδ+0.15sin2δP = 1.4 \sin \delta + 0.15 \sin 2\delta, where δ\delta is the load angle. Newton-Raphson method is used to calculate the value of δ\delta for P=0.8P = 0.8 pu. If the initial guess is 3030^\circ, then its value (in degree) at the end of the first iteration is
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    Question

    A DC voltage source is connected to a series L-C circuit by turning on the switch S at time t=0t = 0 as shown in the figure. Assume i(0)=0,v(0)=0i(0) = 0, v(0) = 0. Which one of the following circular loci represents the plot of i(t)i(t) versus v(t)v(t)?

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    Question

    The equivalent impedance ZeqZ_{eq} for the infinite ladder circuit shown in the figure is

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    Question

    Consider a system governed by the following equationsdx1(t)dt=x2(t)x1(t)\frac{dx_1(t)}{dt} = x_2(t) - x_1(t)dx2(t)dt=x1(t)x2(t)\frac{dx_2(t)}{dt} = x_1(t) - x_2(t)The initial conditions are such that x1(0)<x2(0)<x_1(0) < x_2(0) < \infty. Let x1f=limtx1(t)x_{1f} = \lim_{t \to \infty} x_1(t) and x2f=limtx2(t)x_{2f} = \lim_{t \to \infty} x_2(t). Which one of the following is true?
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    Question

    The number of roots of the polynomial, s7+s6+7s5+14s4+31s3+73s2+25s+200s^7 + s^6 + 7s^5 + 14s^4 + 31s^3 + 73s^2 + 25s + 200, in the open left half of the complex plane is
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    Question

    If CC is a circle z=4|z| = 4 and f(z)=z2(z23z+2)2f(z) = \frac{z^2}{(z^2-3z+2)^2}, then Cf(z)dz\oint_C f(z) dz is
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    Which one of the following statements is true about the digital circuit shown in the figure

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    Question

    Digital input signals A,B,CA, B, C with AA as the MSB and CC as the LSB are used to realize the Boolean function F=m0+m2+m3+m5+m7F = m_0 + m_2 + m_3 + m_5 + m_7, where mim_i denotes the ithi^{th} minterm. In addition, FF has a don't care for m1m_1. The simplified expression for FF is given by
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    Question

    Consider the two continuous-time signals defined below:x1(t)={t,1t10,otherwise,x2(t)={1t,1t10,otherwisex_1(t) = \begin{cases} |t|, & -1 \leq t \leq 1 \\ 0, & \text{otherwise} \end{cases}, \quad x_2(t) = \begin{cases} 1 - |t|, & -1 \leq t \leq 1 \\ 0, & \text{otherwise} \end{cases}These signals are sampled with a sampling period of T=0.25T = 0.25 seconds to obtain discrete-time signals x1[n]x_1[n] and x2[n]x_2[n], respectively. Which one of the following statements is true?
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    Question

    The signal energy of the continuous-time signalx(t)=[(t1)u(t1)][(t2)u(t2)][(t3)u(t3)]+[(t4)u(t4)]x(t) = [(t-1)u(t-1)] - [(t-2)u(t-2)] - [(t-3)u(t-3)] + [(t-4)u(t-4)]is
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    Question

    The Fourier transform of a continuous-time signal x(t)x(t) is given byX(ω)=1(10+jω)2,<ω<X(\omega) = \frac{1}{(10 + j\omega)^2}, -\infty < \omega < \inftywhere j=1j = \sqrt{-1} and ω\omega denotes frequency. Then the value of lnx(t)|\ln x(t)| at t=1t = 1 is ___________ (up to 1 decimal place). (ln\ln denotes the logarithm to base ee)
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    Question

    In the circuit shown in the figure, the bipolar junction transistor (BJT) has a current gain β=100\beta = 100. The base-emitter voltage drop is a constant, VBE=0.7VV_{BE} = 0.7 V. The value of the Thevenin equivalent resistance RThR_{Th} (in Ω\Omega) as shown in the figure is ______ (up to 2 decimal places).

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    Question

    As shown in the figure, CC is the arc from the point (3,0)(3,0) to the point (0,3)(0,3) on the circle x2+y2=9x^2 + y^2 = 9. The value of the integral C(y2+2yx)dx+(2xy+x2)dy\int_C (y^2 + 2yx) dx + (2xy + x^2) dy is _____ (up to 2 decimal places).

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    Question

    Let f(x)=3x37x2+5x+6f(x) = 3x^3 - 7x^2 + 5x + 6. The maximum value of f(x)f(x) over the interval [0,2][0, 2] is _______ (up to 1 decimal place).
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    Question

    Let A = [101120002]\begin{bmatrix} 1 & 0 & -1 \\ -1 & 2 & 0 \\ 0 & 0 & -2 \end{bmatrix} and B=A3A24A+5IB=A^{3}-A^{2}-4A+5I, where I is the 3×33 \times 3 identity matrix. The determinant of B is ________ (up to 1 decimal place).
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    Question

    The capacitance of an air-filled parallel-plate capacitor is 6060 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 8686 pF. Neglecting the fringing effects, the relative permittivity of the dielectric is _____________ (up to 2 decimal places).
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    Question

    The unit step response y(t) of a unity feedback system with open loop transfer function
    G(s)H(s)=K(s+1)2(s+2)G(s)H(s) = \frac{K}{(s+1)^2(s+2)} is shown in the figure. The value of K is ______ (up to 2 decimal places).

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    Question

    A three-phase load is connected to a three-phase balanced supply as shown in the figure. If Van=1000V_{an} = 100 \angle 0^\circ V, Vbn=100120V_{bn} = 100 \angle -120^\circ V and Vcn=100240V_{cn} = 100 \angle -240^\circ V (angles are considered positive in the anti-clockwise direction), the value of R for zero current in the neutral wire is ___________ Ω\Omega (up to 2 decimal places).

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    Question

    The voltage across the circuit in the figure, and the current through it, are given by the following expressions:
    v(t)=510cos(ωt+60)Vv(t) = 5 – 10 \cos(\omega t + 60^\circ) V
    i(t)=5+Xcos(ωt)Ai(t) = 5 + X \cos(\omega t) A
    where ω=100π\omega = 100 \pi radian/s. If the average power delivered to the circuit is zero, then the value of X (in Ampere) is ______ (up to 2 decimal places).

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    Question

    A phase controlled single phase rectifier, supplied by an AC source, feeds power to an R-L-E load as shown in the figure. The rectifier output voltage has an average value given by Vo=Vm2π(3+cosα)V_o = \frac{V_m}{2\pi} (3 + \cos \alpha), where Vm=80πV_m = 80\pi volts and α\alpha is the firing angle. If the power delivered to the lossless battery is 1600 W, α\alpha in degree is________ (up to 2 decimal places).

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    Question

    The figure shows two buck converters connected in parallel. The common input dc voltage for the converters has a value of 100 V. The converters have inductors of identical value. The load resistance is 1 Ω\Omega. The capacitor voltage has negligible ripple. Both converters operate in the continuous conduction mode. The switching frequency is 1 kHz, and the switch control signals are as shown. The circuit operates in the steady state. Assuming that the converters share the load equally, the average value of iS1i_{S1}, the current of switch S1 (in Ampere), is _____ (up to 2 decimal places).
    Circuit diagram of two parallel buck converters and their switch control signals
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    A 3-phase 900 kVA, 3 kV / 3\sqrt{3} kV (Δ\Delta/Y), 50 Hz transformer has primary (high voltage side) resistance per phase of 0.3 Ω\Omega and secondary (low voltage side) resistance per phase of 0.02 Ω\Omega. 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).
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    Question

    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. The total series resistance is 1 Ω\Omega. The magnetic circuit is assumed to be linear. At the same supply voltage, the load torque is increased by 44%. The speed of the motor in r.p.m. (rounded to the nearest integer) is ________ .
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    Question

    A dc to dc converter shown in the figure is charging a battery bank, B2 whose voltage is constant at 150 V. B1 is another battery bank whose voltage is constant at 50 V. The value of the inductor, L is 5 mH and the ideal switch, S is operated with a switching frequency of 5 kHz with a duty ratio of 0.4. Once the circuit has attained steady state and assuming the diode D to be ideal, the power transferred from B1 to B2 (in Watt) is ___________ (up to 2 decimal places).

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    The equivalent circuit of a single phase induction motor is shown in the figure, where the parameters are R1=R2=Xl1=Xl2=12 ΩR_1 = R_2' = X_{l1} = X_{l2}' = 12\text{ }\Omega, XM=240 ΩX_M = 240\text{ }\Omega and ss is the slip. At no-load, the motor speed can be approximated to be the synchronous speed. The no-load lagging power factor of the motor is___________ (up to 3 decimal places).

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    The voltage v(t)v(t) across the terminals aa and bb as shown in the figure, is a sinusoidal voltage having a frequency ω=100\omega = 100 radian/s. When the inductor current i(t)i(t) is in phase with the voltage v(t)v(t), the magnitude of the impedance ZZ (in Ω\Omega) seen between the terminals aa and bb is ________ (up to 2 decimal places).

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