Networks Analysis and Synthesis - Section 1 (3)

Directions to Solve

Networks Analysis and Synthesis - Section 1

17.

The impedance of an RC series circuit is 12 Ω at f= 50 Hz. At f= 200 Hz, the impedance will be

A.	more than 12
B.	less than 3
C.	more than 3 Ω but less than 12 Ω
D.	more than 12 Ω but less than 24 Ω

Answer: Option C

Explanation:

Z = √R2 + XC2. When f is made four times, XC becomes one-fourth but R remains the same.

18.

In an RC series circuit R = 100 Ω and XC = 10 Ω. In this circuit

A.	the current and voltage are in phase
B.	the current leads the voltage by about 6°
C.	the current leads the voltage by about 84°
D.	the current lags the voltage by about 6°

Answer: Option B

Explanation:

In RC circuit the current leads the voltage. 161-201-1

19.

The degree of the nodes 1, 2, 3, 4 is

132-835-1

A.	2
B.	3
C.	2 for 1, 2, 3, and 3 for 4
D.	all 3

Answer: Option D

Explanation:

Degree of node is the no.of branch incident to it.

20.

In the series circuit shown in figure, for series resonance, the value of the coupling coefficient, K will be

134-868-1

A.	0.25
B.	0.5
C.	0.1
D.	1

Answer: Option A

Explanation:

Mutual inductance w_m = ωk√ L₁L₂

1-sym-imp m = √ k. 2. 8j² = 4k. j

Z = 20 - j10 + j2 + j6 + 2.4kj - 2j + 8kj = 0 at resonance

1-sym-imp -2 = -8k

k = 1/4 1-sym-imp 0.25 .

21.

In the circuit of figure the voltage across capacitor when switch is closed at t = ∞ is

94-178-1

A.	0 V
B.	20 V
C.	very large
D.	7.5 V

Answer: Option D

Explanation:

Voltage across capacitor = voltage across 3Ω resistance = 160-183-1

22.

An infinite ladder is constructed with 1 Ω and 2 Ω resistors shown below.

137-899-1

A.	8.18 A
B.	0 A
C.	9 A
D.	can't determined

Answer: Option C

Explanation:

R = 1 + (2 || R)

1-sym-imp R = 2

171-899-1

23.

Which of the following is correct for a driving point functions?

A.	The real parts of all poles must be negative
B.	The real parts of all poles and zeros must be negative
C.	The real parts of all poles and zeros must be negative or zero
D.	The real parts of all zeros must be negative

Answer: Option C

Explanation:

It is a necessary condition for response to be stable.

24.

A 3 phase balanced supply feeds 3 phase unbalanced load. Power supplied to the load can be measured by using

1.2 wattmeter

2.one wattmeter

3.3 wattmeter

Which of the above statements is correct?

A.	1 and 2
B.	1 and 3
C.	2 and 3
D.	3 alone

Answer: Option B

Explanation:

A minimum of 2 wattmeters is required to measure 3 phase power. Of course power can be measured by putting one wattmeter in each phase.

Networks Analysis and Synthesis - Section 1 (3)

Networks Analysis and Synthesis - Section 1

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