This set of Network Theory Multiple Choice Questions & Answers (MCQs) focuses on “Parallel Resonance”.

1. For the circuit shown below, determine its resonant frequency.

a) 6.12

b) 7.12

c) 8.12

d) 9.12

View Answer

Explanation: The resonant frequency of the circuit is f

_{r}= 1/(2π√LC). Given L = 5H and C = 100uf. On substituting the given values in the equation we get resonant frequency = 1/(2π√(5×100×10

^{-6})) = 7.12 Hz.

2. Find the quality factor of the circuit shown in the question 1.

a) 2.24

b) 3.34

c) 4.44

d) 5.54

View Answer

Explanation: The quality factor of the circuit is Q = X

_{L}/R = 2πf

_{r}L/R. Given f = 7.12 Hz and L = 5H and R = 100. On substituting the given values in the equation we get the quality factor = (6.28×7.12×5)/100 = 2.24.

3. Find the bandwidth of the circuit shown in the question 1.

a) 1

b) 2

c) 3

d) 4

View Answer

Explanation: The bandwidth of the circuit is BW = f

_{r}/Q. we obtained f

_{r}= 7.12 Hz and Q = 2.24. On substituting the given values in the equation we get the bandwidth = 7.12/2.24 = 3.178Hz.

4. The magnification in resonance considering the voltage across inductor is?

a) V/V_{L}

b) V_{L}/V

c) V x V_{L}

d) V_{L}

View Answer

Explanation: The ratio of voltage across inductor to the voltage applied at resonance can be defined as magnification. The magnification in resonance considering the voltage across inductor is Q = V

_{L}/V.

5. Considering the voltage across the capacitor, the magnification in resonance is?

a) V_{C}

b) V x V_{C}

c) V_{C}/V

d) V/V_{C}

View Answer

Explanation: The ratio of voltage across capacitor to the voltage applied at resonance can be defined as magnification. Considering the voltage across the capacitor, the magnification in resonance is Q = V

_{C}/V.

_{r}in parallel resonant circuit is?

a) 1/(2√LC)

b) 1/√LC

c) 1/(π√LC)

d) 1/(2π√LC)

View Answer

Explanation: Basically parallel resonance occurs when X

_{L}= X

_{L}. The frequency at which the resonance occurs is called the resonant frequency. The value of ω

_{r}in parallel resonant circuit is ω

_{r}= 1/√LC.

7. The expression of resonant frequency for parallel resonant circuit is?

a) 1/(2π√LC)

b) 1/(π√LC)

c) 1/(2√LC)

d) 1/√LC

View Answer

Explanation: The condition for resonance occurs when X

_{L}= X

_{L}. The expression of resonant frequency for parallel resonant circuit is f

_{r}= 1/(2π√LC).

8. Find the resonant frequency in the ideal parallel LC circuit shown in the figure.

a) 7.118

b) 71.18

c) 711.8

d) 7118

View Answer

Explanation: The expression for resonant frequency is f

_{r}= 1/(2π√LC). Given L = 50mH and C = 0.01uF. On substituting the given values in the equation we get the resonant frequency = 1/(2π√(50×10

^{-3})×0.01×10

^{-6}) ))=7117.6 Hz.

9. If the value of Q of the circuit is high, then its effect on bandwidth is?

a) large bandwidth

b) small bandwidth

c) no effect on bandwidth

d) first increases and then decreases

View Answer

Explanation: If the value of Q of the circuit is high, then small bandwidth because bandwidth is inversely proportional to the quality factor.

10. If in a circuit, if Q value is decreased then it will cause?

a) small bandwidth

b) no effect on bandwidth

c) first increases and then decreases

d) large bandwidth

View Answer

Explanation: If in a circuit, if Q value is decreased then bandwidth increases and the bandwidth do not decrease.

**Sanfoundry Global Education & Learning Series – Network Theory.**

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