Electric Circuits - Online Test
Q1.
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
Answer : Option B
Explaination / Solution:
In the equivalent star connection, the resistance can be given as
Q2. The circuit shown below is driven by a sinusoidal input Vi = Vpcos(t/RC). The
steady state output vo
Answer : Option A
Explaination / Solution:
parallel combination of R and C equivalent impedance is
Transfer function can be written as
Q3. The transfer function 
Answer : Option D
Explaination / Solution:
For the given capacitance, 
in the circuit, we have the reactance.
in the circuit, we have the reactance.
Q4. A source 
has an internal impedance of 
If a purely resistive load connected to this source has to extract the maximum power out of the source, its value inΩ should be
has an internal impedance of If a purely resistive load connected to this source has to extract the maximum power out of the source, its value inΩ should be
Answer : Option C
Explaination / Solution:
For the purely resistive load, maximum average power is transferred when
where
is the equivalent thevinin (input) impedance of the circuit. Hence,
we obtain
where
is the equivalent thevinin (input) impedance of the circuit. Hence,we obtain
Q5. In the circuit shown below, the Norton equivalent current in amperes with
respect to the terminals P and Q is
Answer : Option A
Explaination / Solution:
Replacing P - Q by short circuit as shown below we have
Using current divider rule the current ISC is
Q6. In the circuit shown below, the value of RL such that the power transferred to RL is maximum is
Answer : Option C
Explaination / Solution:
Power transferred to RL will be maximum when RL is equal to the thevenin
resistance. We determine thevenin resistance by killing all source as follows :
Q7. In the circuit shown below, the current I is equal to
Answer : Option B
Explaination / Solution:
From star delta conversion we have
Replacing in circuit we have the circuit shown below :
Now the total impedance of circuit is
Q8. In the circuit shown below, the initial charge on the capacitor is 2.5 mC, with
the voltage polarity as indicated. The switch is closed at time t = 0. The current i(t) at a time t after the switch is closed is
Answer : Option A
Explaination / Solution:
Here we take the current flow direction as positive.
Q9. 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?
Answer : Option A
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.
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 ).
Q10. In the circuit shown below, if the source voltage 
then the
Thevenin’s equivalent voltage in Volts as seen by the load resistance RL is
then the
Thevenin’s equivalent voltage in Volts as seen by the load resistance RL is
Answer : Option C
Explaination / Solution:
No Explaination.
