Electric Circuits - Online Test
Q1. 
In the interconnection of ideal sources shown in the figure, it is known that the 60 V source is absorbing power.
Which of the following can be the value of the current source I ?
Answer : Option A
Explaination / Solution:
Circuit is as shown below
Since 60 V source is absorbing power. So, in 60 V source current flows from + to - ve direction So,
I + I1 = 12
I = 12 - I1
I is always less then 12 A So, only option (A) satisfies this conditions.
Q2. If the transfer function of the following network is
Answer : Option C
Explaination / Solution:
Q3. In the given circuit, the values of V1 and V2 respectively are
Answer : Option A
Explaination / Solution:
By Nodal analysis
Q4. A function 1 – x2 + x3 is defined in the closed interval [-1, 1]. The value of x , in the open interval (-1, 1) for which the mean value theorem is satisfied, is
Answer : Option B
Explaination / Solution:
Lagrange’s mean value theorem states that if a function f(x) is continuous in close interval [a, b] and differentiable in open interval (a + b), then for point c in the interval, we may define
Since, polynomial function is always continuous and differentiable, so
Q5. The damping ratio of a series RLC circuit can be expressed as
Answer : Option C
Explaination / Solution:
Damping ratio is given by
Q6. 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
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
Q7. Consider the configuration shown in the figure which is a portion of a larger
electrical network
For R = 1Ω and currents i1 = 2 A, i4 =- 1 A, i5 =- 4 A, which one of the
following is TRUE ?
Answer : Option A
Explaination / Solution:
From the circuit, we have
i2 = i4 + i1
= -1 + 2
= 1A
i3 = i5 + i2
= -4 + 1
= -3A
i6 = i1 – i3
= 2 - (-3)
= 5A
Q8. A two-port network has scattering parameters given by 
If the
port-2 of the two port is short circuited, the S11 parameter for the resultant one
If the
port-2 of the two port is short circuited, the S11 parameter for the resultant one
Answer : Option B
Explaination / Solution:
No Explaination.
Q9. A 230 V rms source supplies power to two loads connected in parallel. The first load draws 10 kW at 0.8 leading power factor and the second one draws 10 kVA at 0.8 lagging power factor. The complex power delivered by the source is
Answer : Option B
Explaination / Solution:
Consider the circuit diagram for given problem as shown below
Load delivered to Z1 is
P1 = 10 kW
cos ϕ1
= 0.8, leading
So, we obtain the complex power delivered to Z1 as
Again, the delivered power to load Z2 as
|s1|= 10 kVA
cos ϕ2 = 0.8, lagging
So, we obtain the complex power delivered to load Z2 as
Hence, the total complex power delivered by the source is
s1 + s2 = (10 – j7.5) + (8
+ j6)
= (18 - j1.5) kVA
Q10. The built-in potential of the junction
Answer : Option B
Explaination / Solution:
We know that
