In a two-port network, the transmission (ABCD) parameters are also called:

 

Q1. A network has 'n' nodes and 'i' independent loops. The number of branches in the network is:

                            (A)    n - 1

(B)    i + n - 1

(C)   n + 1

(D)    i + n + 1

Q2. For a network graph with B branches and N nodes, the number of independent loops is:

                            (A)    B - N + 1

(B)    N - 1

(C)   B + N

(D)    B - 1

Q3. The h-parameters of a two-port network consisting of a single 1-ohm resistor in shunt (between input and output common node) are h = ?

                            ( A)    [[0,1],[1,-1]]

(B)    [[0,-1],[-1,1]]

(C)   [[0,-1],[1,1]]

(D)    [[0,1],[-1,1]]

Q4. A 10-ohm resistive load is impedance-matched by a transformer to a source of 6250-ohm internal resistance. The primary-to-secondary turns ratio is:

                            (A)    10

(B)    15

(C)   20

(D)    25

Q5. For maximum power transfer, a 10-ohm load is matched to a 6250-ohm source. The turns ratio N1/N2 = sqrt(6250/10) equals:

                            (A)    10

(B)    15

(C)   20

(D)    25

Q6. In a circuit, a voltage source V feeds a resistor R in parallel with a current-controlled source 'a·i1'. The power delivered by the source as a function of 'a' is:

                            (A)    V²/R

(B)    (1-a)V²/R

(C)   (1+a)V²/R

(D)    -V²/R

Q7. The Superposition theorem can be applied to compute:

                            (A)    Power directly

(B)    Branch currents and voltages

(C)   Only resistance

(D)    Energy directly

Q8. Maximum power transferred to a load equals Vth²/(4Rth). The efficiency at this condition is:

                        (A)    100%

 

 

(C)    50%

(D)     25%

Q9. In a series RLC circuit with R = 230 ohm, supply 230 V, 50 Hz. Removing C, current lags by 30 deg; removing L, current leads by 30 deg. The power dissipated is:

                            (A)    305 W

(B)    210 W

(C)   Zero

(D)    230 W

Q10. A series RLC circuit shows equal lag (removing C) and lead (removing L) of 30 deg. This means the circuit is at:

                            (A)    Cut-off

(B)    Resonance

(C)   Half-power point

(D)    Maximum reactance

Q11. At resonance in a series RLC circuit, the impedance equals:

                            (A)    Maximum

(B)    Minimum (= R)

(C)   Zero

(D)    Infinite

Q12. The resonant frequency of a series RLC circuit with L = 1 H and C = 1 uF is approximately:

(A)    159 Hz

(B)    1000 Hz

(C)   318 Hz

(D)    50 Hz

Q13. At resonance, a series RLC circuit draws maximum current because impedance is minimum. The power factor is:

                            (A)    Zero

(B)    0.5

(C)   Unity

(D)    0.707

Q14. Apparent power S, active power P and reactive power Q are related by:

                            (A)    S = P + Q

(B)    S² = P² + Q²

(C)   S = P - Q

(D)    S = P x Q

Q15. The power consumed by a pure inductor over one complete AC cycle is:

                            (A)    VI

(B)    Maximum

(C)   Zero

(D)    I²R

Q16. An AC is measured by a rectifier ammeter (reads 31 A) and a hot-wire ammeter (reads 33 A). The form factor is:

                            (A)    1.064

(B)    1.11

(C)   1.0

(D)    0.9393

 

 

Q17. A rectifier-type (moving coil) instrument reads the value of an alternating quantity:

                            (A)    RMS

(B)    Peak

(C)   Average

(D)    Instantaneous

Q18. A hot-wire (thermal) instrument reads the value of an alternating quantity:

                            (A)    Average

(B)    RMS

(C)   Peak

(D)    Zero

Q19. The form factor of a pure sinusoidal waveform is:

                            (A)    1.0

(B)    1.11

(C)   1.414

(D)    0.637

Q20. The RMS value of a sinusoid of peak 100 V is:

(A)    70.7 V

(B)    63.7 V

(C)   100 V

(D)    141.4 V

Q21. For a sine wave, the peak factor (crest factor) equals:

                            (A)    1.11

(B)    1.414

(C)   0.707

(D)    2.0

Q22. Equivalent inductance is found for a coupled-coil network with self and mutual inductances. With the given coupled network (10H/15H mutual, 25/30/35H self), the equivalent inductance is:

                            (A)    60/9 H

(B)    9/60 H

(C)   50/9 H

(D)    9/50 H

Q23. Two coils with self-inductances L1 and L2 and mutual inductance M, connected series-aiding, have total inductance:

                            (A)    L1 + L2

(B)    L1 + L2 - 2M

(C)   L1 + L2 + 2M

(D)    L1 + L2 + M

Q24. Two coils in series-opposing connection have total inductance:

                            (A)    L1 + L2 + 2M

(B)    L1 + L2 - 2M

(C)   L1 + L2

(D)    L1 - L2

Q25. The coefficient of coupling k between two coils is given by:

                            (A)    M/(L1·L2)

(B)    M/sqrt(L1·L2)

 

 

(D) M²/(L1·L2)

Q26. A balanced Maxwell bridge gives the unknown values Rx and Lx. For the given bridge (2000, 750, 4000 ohm, 0.05 uF), the values are:

                            (A)    75 ohm, 75 mH

(B)    75 ohm, 150 mH

(C)   375 ohm, 75 mH

(D)    37.5 ohm, 75 mH

Q27. A Wheatstone bridge has R1 = 50, R2 = 65, R3 = 100 ohm, each with +/-0.5% tolerance. The upper and lower limits of unknown Rx are:

                            (A)    65.675, 64.325

(B)    65.65, 64.35

(C)   131.95, 128.05

(D)    131.30, 128.70

Q28. Maxwell's bridge is used for the measurement of:

                            (A)    Capacitance

(B)    Inductance (medium Q coils)

(C)   Resistance only

(D)    Frequency

Q29. Identify correct: 

(i) Owen's bridge measures inductance in terms of capacitance 

(ii) Hay's bridge is for high-Q coils

(iii) Campbell bridge measures mutual inductance 

(iv) Anderson bridge precisely measures inductance:

                           (A)    (i) and (ii) only

(B)    (ii) and (iii) only

(C)   (iii) and (iv) only

(D)    (i) and (iv) only

Q30. Anderson's bridge is a modification of which bridge, used for precise inductance measurement?

                            (A)    Wien bridge

(B)    Maxwell bridge

(C)   Schering bridge

(D)    De Sauty bridge

Q31. For a circuit with sources 2V, 4V and resistors, the potential difference VXY between points X and Y is found to be:

                            ( A)    X higher by 3.7 V

(B)    X lower by 3.7 V

(C)   X lower by 4.3 V

(D)    X higher by 4.3 V

Q32. An ideal diode in series with a 4-ohm resistor across a 10 V source, with a 1-ohm branch and 2 A source. The diode current iD and VAB are:

                           (A)    0 A, 5 V

(B)    1 A, 5 V

(C)   1 A, 3 V

(D)    3 A, 5 V

Q33. For an ideal diode to conduct, the diode must be:

                            (A)    Reverse biased

(B)    Forward biased

(C)   Open

 

 

 

Q34. Two identical coaxial circular coils carry equal currents in opposite directions. The magnetic field B at the midpoint on the axis is:

(A)    Zero

(B)    Same as one coil

(C)   Twice that of one coil

(D)    Half that of one coil

Q35. Which statements are WRONG for 3-phase RYB (clockwise):

(i) balanced delta line currents lag phase currents by 30 deg

 (ii) balanced star line currents lag phase by 30 deg 

(iii) balanced star line voltages lead phase by 30 deg 

(iv) balanced delta line voltages lag phase by 30 deg

                            (A)    (i) and (ii) only

(B)    (ii) and (iv) only

(C)   (iii) and (iv) only

(D)    (i) and (iv) only

Q36. In a balanced star-connected system, the line voltage is      times phase voltage:

                            (A)    1

(B)    sqrt(3)

(C)   1/sqrt(3)

(D)    3

Q37. In a balanced delta-connected system, the line current is     times phase current:

                           (A)    1

(B)    sqrt(3)

(C)   1/sqrt(3)

(D)    3

Q38. Two-wattmeter method: which are correct? 

(i) Both read equal power if PF angle is 0 deg 

(ii) One reads negative if PF angle > 60 deg

(iii) Only one reads total power if PF angle is 30 deg:

(A)    (i) and (ii)

(B)    (ii) and (iii)

(C)   (iii) and (i)

(D)    (i),(ii) and (iii)

Q39. In the two-wattmeter method, the total three-phase power equals:

                            (A)    W1 - W2

(B)    W1 x W2

(C)   W1 + W2

(D)    (W1+W2)/2

Q40. In a 3-phase 400V 4-wire system, a 230V 100W lamp on R-phase and 230V 200W lamp on Y-phase. If neutral breaks, then:

                            (A)    200 W lamp fuses first

(B)    100 W lamp fuses first

(C)   Both lamps glow normally

(D)    Both fuse together

Q41. When the neutral of an unbalanced star load breaks, the lamp with             resistance gets higher voltage and fuses:

                            (A)    Lower (higher wattage)

(B)    Higher (lower wattage)

(C)   Equal

(D)    Zero

 

 

 

Q42. Which is INCORRECT about hysteresis loops:

(i) coercivity of hard > soft 

(ii) hard loop area is less than soft 

(iii) retentivity of hard S soft are always equal:

                            (A)    (i) only

(B)    (i) and (ii) only

(C)   (i),(ii) and (iii)

(D)    (ii) and (iii) only

Q43. A hard magnetic material compared to a soft magnetic material has:

                            (A)    Smaller hysteresis loop

(B)    Larger hysteresis loop area

(C)   Lower coercivity

(D)    Equal retentivity

Q44. Match: Electrostatic field, Magnetostatic field, Gauss law point form to curl/divergence relations. The correct match is:

                           (A)    X-P; Y-R; Z-T

(B)    X-P; Y-S; Z-T

(C)   X-Q; Y-S; Z-U

(D)    X-Q; Y-R; Z-U

Q45. For a static electric field, the curl is:

                            (A)    Non-zero

(B)    Zero

(C)   Infinite

(D)    Equal to J

Q46. KCL is based on the conservation of:

                            (A)    Energy

(B)    Charge

(C)   Momentum

(D)    Mass

Q47. KVL is based on the conservation of:

                            (A)    Charge

(B)    Energy

(C)   Momentum

(D)    Power

Q48. At the instant of switching (t=0), an uncharged capacitor behaves as a:

                            (A)    Open circuit

(B)    Short circuit

(C)   Resistor

(D)    Current source

Q49. At steady state in a DC circuit, an inductor behaves as a:

                            (A)    Open circuit

(B)    Short circuit

(C)   Capacitor

(D)    Resistor

Q50. The time constant of an RL circuit is:

                            (A)    R

                            (B)    L/R

                            (C)    1/RC

  

(D) LC

Q51. The time constant of an RC circuit is:

                            (A)    L/R

(B)    RC

(C)   R/C

(D)    1/RC

Q52. For three equal resistors R in delta, each equivalent star resistor is:

                            (A)    3R

(B)    R

(C)   R/3

(D)    R/sqrt(3)

Q53. In a purely capacitive AC circuit, the current   the voltage by 90 degrees:

                            (A)    Lags

(B)    Leads

(C)   Is in phase with

(D)    Opposes

Q54. The quality factor Q of a series resonant circuit is given by:

                            (A)    R·sqrt(C/L)

(B)    (1/R)·sqrt(L/C)

(C)   sqrt(LC)

(D)    R/sqrt(LC)

Q55. Bandwidth of a resonant circuit is related to resonant frequency fr and Q by:

                        (A)    BW = Q·fr

(B)    BW = fr/Q

(C)   BW = fr·Q²

(D)    BW = Q/fr

Q56. The impedance of an inductor at angular frequency w is:

                            (A)    R

(B)    jwL

(C)   1/jwC

(D)    wC

Q57. Norton's equivalent is a current source in parallel with:

                            (A)    An inductor

(B)    A capacitor

(C)   A resistance

(D)    A voltage source

Q58. Thevenin resistance Rth is found by:

                            (A)    Open-circuiting the load and keeping sources

(B)    Turning off all independent sources and looking into terminals

(C)   Short-circuiting the source

(D)    Measuring load current

Q59. The reciprocal of impedance is called:

                        (A)    Reactance

(B)    Conductance

(C)   Admittance

 

 

Q60. A network is said to be linear if it obeys:

                            (A)    Only Ohm's law

(B)    Superposition and homogeneity

(C)   Only KCL

(D)    Only KVL

Q61. For maximum power transfer in an AC circuit, the load impedance must equal the:

                            (A)    Source impedance

(B)    Complex conjugate of source impedance

(C)   Reciprocal of source impedance

(D)    Square of source impedance

Q62. Energy stored in a capacitor of capacitance C charged to voltage V is:

                            (A)    ½ LI²

(B)    ½ CV²

(C)   CV

(D)    I²R

Q63. Energy stored in an inductor carrying current I is:

                            (A)    ½ CV²

(B)    ½ LI²

(C)   LI

(D)    V²/R

Q64. The driving-point impedance of a network is the ratio of:

(A)    Voltage to current at the same port

(B)    Output to input voltage

(C)   Current to voltage at different ports

(D)    Power to current

Q65. In a two-port network, the transmission (ABCD) parameters are also called:

                            (A)    Hybrid parameters

(B)    Chain parameters

(C)   Impedance parameters

(D)    Admittance parameter

Q66. A 250 V DC shunt motor with armature 0.2 ohm draws 41 A at 800 rpm. With 2 ohm added in series during stalling, the ratio of stalling torque to full-load torque is about:

                          (A)    1.42

(B)    2.84

(C)   1.25

(D)    3.13

Q67. The slip speed of a 3-phase 4-pole 50 Hz induction motor whose rotor current period is 200 ms (rotor frequency 5 Hz):

(A)    150 rpm

(B)    1350 rpm

(C)   75 rpm

(D)    1425 rpm

Q68. A short-shunt DC compound generator supplies 100 A at 250 V, with shunt field 130 ohm, armature 0.1 ohm, series field 0.1 ohm, brush drop 1 V/brush. The generated EMF is about:

                             (A)    270.2 V

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(C)    262.2 V

(D)     272.2 V