Topic: Electric Circuits (Test 5)



Topic: Electric Circuits
Q.1
The voltage applied to a circuit is  volts and the circuit draws a current of  amperes. Taking the voltage as the reference phasor, the phasor representation of the current in amperes is 
A.
B.
C.
D.
Answer : Option B
Explaination / Solution:



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Q.2
 RA and RB are the input resistances of circuits as shown below. The circuits extend infinitely in the direction shown. Which one of the following statements is TRUE?

A. R= RB 
B. R= RB = 0
C. R< RB 
D. R= RA/(1+RA
Answer : Option D
Explaination / Solution:



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Q.3
The input voltage given to a converter is
The current drawn by the converter is 

The active power drawn by the converter is
A. 181W
B. 500W
C. 707W
D. 887W
Answer : Option B
Explaination / Solution:



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Q.4
For maximum power transfer between two cascaded sections of an electrical network, the relationship between the output impedance Z1 of the first section to the input impedance Z2 of the second section is
A. Z2 = Z1
B. Z2 = -Z1
C.

Z2 = Z1*

D.

Z2 = -Z1*

Answer : Option C
Explaination / Solution:

Consider the cascaded network shown below

Since, the output impedance of system 1 is Z1 and input impedance of system 2 is Z2. So, we have the equivalent circuit is

Now, we consider a circuit with internal impedance Zin and load impedance ZL

For maximum power transfer, the condition is

Zin* = Z2

Comparing this condition to cascaded system, we have the required condition for maximum power transfer as
Z1* = Z2

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Q.5
The impedance looking into nodes 1 and 2 in the given circuit is

A. 50 Ω
B. 100 Ω
C. 5 kΩ
D. 10.1 kΩ
Answer : Option A
Explaination / Solution:




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Q.6
In the following figure, C1 and C2 are ideal capacitors. C1 has been charged to 12 V before the ideal switch S is closed at t = 0. The current i(t) for all t is 

A. zero
B. a step function
C. an exponentially decaying function
D. an impulse function
Answer : Option D
Explaination / Solution:

Time constant = RC In the given circuit, R = 0 Rise time = 0; hence capacitor charges instantaneously and the current can be represented as impulse function

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Q.7
Two passive two-port networks are connected in cascade as shown in figure. A voltage source is connected at port 1.

Given V1 = A1V2 + B1I2

           I1 = C1V2 + D1I2

           V2 = A2V3 + B2I3

           I2 = C2V3 + D2I3
A1 ,B1 ,C1 ,D1 ,A2 ,B2 ,C2 and Dare the generalized circuit constants. If the Thevenin equivalent circuit at port 3 consists of a voltage source VT and impedance ZT connected in series, then
A.
B.
C.
D.
Answer : Option D
Explaination / Solution:



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Q.8
Consider a delta connection of resistors and its equivalent star connection as shown below. If all elements of the delta connection are scaled by a factor k, k>0, the elements of the corresponding star equivalent will be scaled by a factor of

A.
B. K
C. 1/K
D.
Answer : Option B
Explaination / Solution:
No Explaination.


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Q.9
The switch in the circuit has been closed for a long time. It is opened at t = 0. At t = 0+, the current through the 1µF capacitor is
 
A. 0A
B. 1A
C. 1.25A
D. 5A
Answer : Option B
Explaination / Solution:
No Explaination.


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Q.10
If the electrical circuit of figure (b) is an equivalent of the coupled tank system of figure (a), then

A. A, B are resistances and C, D capacitances
B. A, C are resistances and B, D capacitances
C. A, B are capacitances and C, D resistances
D. A, C are capacitances and B, D resistances
Answer : Option D
Explaination / Solution:
No Explaination.


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