# Electric Circuits (Test 6)

## Gate Exam : Ee Electrical Engineering

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Electric Circuits
| Electric Circuits |
Q.1
The transfer function

A.
B.
C.
D.
Explaination / Solution:

For the given capacitance, in the circuit, we have the reactance.

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Q.2
Two magnetically uncoupled inductive coils have Q factors q1 and q2 at the chosen operating frequency. Their respective resistances are R1 and R2 . When connected in series, their effective Q factor at the same operating frequency is
A.
B.
C.
D.
Explaination / Solution:
No Explaination.

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Q.3
The two-port network P shown in the figure has ports 1 and 2, denoted by terminals (a, b) and (c, d), respectively. It has an impedance matrix Z with parameters denoted by zij. A 1Ω resistor is connected in series with the network at port 1 as shown in the figure. The impedance matrix of the modified two-port network (shown as a dashed box) is

A.
B.
C.
D.
Explaination / Solution:
No Explaination.

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Q.4
In the circuit shown, the switch S is open for a long time and is closed at t = 0. The current i (t) for t  0+is

A. i (t) = 0.5 - 0.125e-1000tA
B. i (t) = 1.5 - 0.125e-1000tA
C. i (t) = 0.5 - 0.5e-1000tA
D. i (t) = 0.375e-1000tA
Explaination / Solution:

When the switch S is open for a long time before t < 0, the circuit is

At t = 0, inductor current does not change simultaneously, So the circuit is

Current is resistor (AB)
i(0) = 0.75/2 = 0.375 A
Similarly for steady state the circuit is as shown below

B = 0.375 - 0.5 =- 0.125

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Q.5
The L-C circuit shown in the figure has an inductance L = 1mH and a capacitance C = 10µF.

The initial current through the inductor is zero, while the initial capacitor voltage is 100 V. The switch is closed at t = 0. The current i through the circuit is:
A. 5cos(5×103t)A
B. 5sin(104t)A
C. 10cos(5×103t)A
D. 10sin(104t)A
Explaination / Solution:
No Explaination.

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Q.6
The current through the 2 kΩ resistance in the circuit shown is

A. 0mA
B. 1mA
C. 2mA
D. 6mA
Explaination / Solution:

It is a balanced Wheatstone bridge.

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Q.7
A network consisting of a finite number of linear resistor (R), inductor (L), and capacitor (C) elements, connected all in series or all in parallel, is excited with a source of the form

The source has nonzero impedance. Which one of the following is a possible form of the output measured across a resistor in the network?
A.
B.
C.
D.
Explaination / Solution:

The property of any LTI system or network is if the excitation contains „n‟ number of different frequency then the response also contains exactly n number of different frequency term and the output frequency and input frequency must be same however depending on components there is a possible change in amplitude and phase but never the frequency.
⟶ If the source has 3 frequency terms as given then any voltage or any current of any element should have also 3 terms based on this option (B) and (D) are eliminated.
If we take option (C). It has 3 frequency term but it also suggest there is a phase change so ϕk but amplitude must be same as input as ak is present which may not be true always.
⟶ So option (A) is correct, as it suggest frequency term of output and inputs are same with possible change in amplitude and phase, because we have (bk and ϕk ).

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Q.8
A series RL circuit is excited at t = 0 by closing a switch as shown in the figure. Assuming zero initial conditions, the value of  is

A. V/L
B. -V/R
C. 0
D.
Explaination / Solution:

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Q.9
Three capacitors C1, C2 and C3 whose values are 10 μF , 5 μF , and 2 μF respectively, have breakdown voltages of 10 V, 5 V and 2 V respectively. For the interconnection shown below, the maximum safe voltage in Volts that can be applied across the combination, and the corresponding total charge in μC stored in the effective capacitance across the terminals are respectively

A. 2.8 and 36
B. 7 and 119
C. 2.8 and 32
D. 7 and 80