This set of Network Theory Multiple Choice Questions & Answers (MCQs) focuses on “Dot Convention in Magnetically Coupled Circuits”.

1. In the circuit given below, the input impedance Z_{IN} of the circuit is _________

a) 0.52 – j4.30 Ω

b) 0.52 + j15.70 Ω

c) 64.73 + j17.77 Ω

d) 0.3 – j33.66 Ω

2. The switch in the circuit shown was on position X for a long time. The switch is then moved to position Y at time t=0. The current I(t) for t>0 is ________

a) 0.2e^{-125t}u(t) mA

b) 20e^{-1250t}u(t) mA

c) 0.2e^{-1250t}u(t) mA

d) 20e^{-1000t}u(t) mA

3. A series RLC circuit has a resonance frequency of 1 kHz and a quality factor Q = 100. If each of R, L and C is doubled from its original value, the new Q of the circuit is _____________

a) 25

b) 50

c) 100

d) 200

4. In the circuit shown, the voltage source supplies power which is _____________

a) Zero

b) 5 W

c) 10 W

d) 100 W

5. Initial voltage on capacitor VO as marked |V_{O}| = 5 V, V_{S} = 8 u (t), where u (t) is the unit step. The voltage marked V at t=0^{+} is _____________

a) 1 V

b) -1 V

c) 133 V

d) –133 V

6. In the circuit given below, for time t<0, S_{1} remained closed and S_{2} open., S_{1} is initially opened and S_{2} is initially closed. If the voltage V_{2} across the capacitor C_{2} at t=0 is zero, the voltage across the capacitor combination at t=0^{+} will be ____________

a) 1 V

b) 2 V

c) 1.5 V

d) 3 V

7. In the circuit shown below the current I(t) for t≥0^{+} (assuming zero initial conditions) is ___________

a) 0.5-0.125e^{-1000t} A

b) 1.5-0.125e^{-1000t} A

c) 0.5-0.5e^{-1000t} A

d) 0.375e^{-1000t} A

8. For a unit step signal u (t), the response is V_{1} (t) = (1-e^{-3t}) for t>0. If a signal 3u (t) + δ(t) is applied, the response will be (considering zero initial conditions)?

a) (3-6e^{-3t})u(t)

b) (3-3e^{-3t})u(t)

c) 3u(t)

d) (3+3e^{-3t})u(t)

9. In the circuit given below, the switch S_{1} is initially closed and S_{2} is opened. The inductor L carries a current of 10A and the capacitor is charged to 10 V with polarities as shown. The current through C during t=0^{+} is _____________

a) 55 A

b) 5.5 A

c) 45 A

d) 4.5 A

10. An ideal capacitor is charged to a voltage V_{O} and connected at t=0 across an ideal inductor L. If ω = 1LC√, the voltage across the capacitor at time t>0 is ____________

a) V_{O}

b) V_{O} cos(ωt)

c) V_{O} sin(ωt)

d) V_{O} e^{-ωt}cos(ωt)

11. In the circuit given below, the capacitor initially has a charge of 10 C. The current in the circuit at t=1 sec after the switch S is closed will be ___________

a) 14.7 A

b) 18.5 A

c) 40 A

d) 50 A

12. In the circuit given below, the switch S_{1} is initially closed and S_{2} is opened. The inductor L carries a current of 10A and the capacitor is charged to 10 V with polarities as shown. The current through L during t=0^{+} is _____________

a) 55 A

b) 5.5 A

c) 45 A

d) 4.5 A

13. In the figure given below, what is the RMS value of the periodic waveform?

a) 26–√ A

b) 62–√ A

c) 43−−√ A

d) 1.5 A

14. In the circuit given below, the switch is closed at time t=0. The voltage across the inductance just at t=0^{+} is ____________

a) 2 V

b) 4 V

c) -6 V

d) 8 V

15. A rectangular voltage wave of magnitude A and duration B is applied to a series combination of resistance R and capacitance C. The voltage developed across the capacitor is ____________

a) A[1 – exp(-BRC)]b) ABRC

c) A

d) A exp(-BRC)