Practice Network Theory MCQ with Answers.

**Network Theory MCQ with Answers**

**Q1. A generator produces 100 A of current at 4000 V. By using a transformer, the voltage is stepped up to 2.4. 10 ^{5} V so that it can be sent to a village on high voltage lines. If the effective resistance of the line is 30 ohms, the power lost in communication is**

(a) 63.7 W

(b) 83.7 W

(c) 33.7 W

(d) 93.7 W

**Q2. A 40 uF capacitor is connected to a 50 Ω resistor and a generator whose r.m.s. output is 30 volts at 60 Hz The r.m.s. current is**

(a) 0.182 A

(b) 0.061 A

(c) 0.361 A

(d) 0.421 A

**Q3. If two 100 W bulbs are connected in series across 230 V supply, then total power consumed by both the bulbs**

(a) 200 W

(b) 100 W

(C) 50 W

(d) 25 W

**4. In the network of figure shown below, V _{s} = 6V. The time constant of the network is**

(a) 8 sec

(b) 12 sec

(C) 24 sec

(d) 36 sec

**Q5. Following cannot be used as a core of a transformer**

(a) Air

(b) Steel

(c) Aluminium

(d) Ferrite

**Q6. A transformer is used to change**

(a) power

(b) frequency

(c) inductance

(d) voltage

**Q7. The SI unit of inductance times capacitance is**

(a) second

(b) ohm

(c) hertz

(d) square second

**Q8. A solenoid has an inductance of 50 henry and a resistance of 30 ohm . If it is connected to 100 V battery, then how long will it take for the current to reach one-half of its final steady state value?**

(a) 1.45 sec

(b) 1.15 sec

(d) 1.35 sec

(d) 1.25 sec

**Q9. In electrical circuits, the analog of moment of inertia in rotational motion is**

(a) resistance

(b) inductance

(c) capacitance

(d) voltage

**Q10. A box of resistors is labelled R ± x% where R is the mean value and x is the tolerance i.e. the rms deviatior given as a percentage of the mean value. Iftwo resistors from a box labelled 10 KΩ ± 5% are connected ir series the equivalent resistance can be labelled 20KΩ ± x% where x is given by**

(a) ^{5}/_{√(2)}

(b) 5

(c) 5√(2)

(d) 10

**Q11. In a purely inductance AC source circuit L = 50 mH. The inductive reactance of the circuit when the frequency of AC source is 60 Hz, will be**

(a) 18.85 ohm

(b) 3.8 ohm

(c) 6.31 ohm

(d) 12.62 ohm

**Q12. The phase difference (δ) between input and output voltage for the following circuits (i) and (ii)**

will be in negative phase

(a) 0 and 0

(b) π/2 and 0 < δ ≤ ^{π}/_{2} respectively

(c) π/2 and π/2

(d) 0 and 0 < δ ≤ ^{π}/_{2} respectively

Q13. In the following RC circuit, the capacitor was charged in two different ways.

(i) The capacitor was first charged to 5V by moving the toggle switch to position P and then it was charged to 10V by moving the toggle switch to position Q

(ii) The capacitor was directly charged to 10V, by keeping the toggle switch at position Q. Assuming the capacitor to be ideal, which one of the following statements is correct?

(a) The energy dissipation in cases (i) and (ii) will be equal and non-zero

(b) The energy dissipation for case (i) will be more than that for case (ii)

(c) The energy dissipation for case (i) will be less than that for case (ii)

(d) The energy will not be dissipated in either case

**Q14. In the circuit given below, a person measures 9.0 V across the battery, 3.0 V across the 2MΩ resistor R, and 4.5 V across the unknown resistor R _{b}, using an ordinary voltmeter which has a finite input resistance Assuming that the battery has negligible internal resistance, it follows that (i) the resistance R_{b} and (ii) the input resistance r of the voltmeter are, in M Ω**

(a) R_{b} = 3.0, r = 1.0

(b) R_{b} = 2.5, r = 7.5

(c) R_{b} = 4.0, r = 12.0

(d) R_{b} = 4.5, r = 10.0

**Q15. The current read by the ammeter (A) in the circuit given below is**

(a) 27.3 mA

(b) 100.0 mA

(c) 54.5 mA

(d) 50.0 mA

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*Answer Key* (if you find any answer wrong, feel free to Correct us)

*Answer Key*

01. | (b) | 06. | (d) | 11. | (c) |

02. | (c) | 07. | (d) | 12. | (d) |

03. | (a) | 08. | (b) | 13. | (c) |

04. | (a) | 09. | (c) | 14. | (a) |

05. | (c) | 10. | (a) | 15. | (d) |