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 + xis 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
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 Zas

|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