Online Electronics and Communication Engineering Test - Networks Analysis and Synthesis Test 1

Instruction:

• This is a FREE online test. DO NOT pay money to anyone to attend this test.
• Total number of questions : 20.
• Time alloted : 30 minutes.
• Each question carry 1 mark, no negative marks.
• DO NOT refresh the page.
• All the best :-).

1.

In an R-C series circuit excited by a voltage E, the charge across capacitor at t = 0+ is

A.
 0
B.
 CE
C.
 CE (1 - e-t/RC)
D.
 none of the above

Explanation:

Voltage across a capacitor cannot change instantaneously.

2.

In an unloaded transformer, the fluxes limiting the primary and secondary are 30 mWb and 20 mWb. The coefficient of coupling is

A.
 1
B.
 0.1
C.
 0.33
D.
 0.67

Explanation:

Φ11 = (1 - k) Φ1 φ11 = φ1 - φ2

30 - 20 10 mWb

10 mWb = (1 - k) 30m 0.33 = 1 - k k = 0.67 .

3.

In following circuit, steady state is reached with S open, S is closed at t = 0, the current I at t = 0+ is given by

A.
 9 Ω
B.
 6 Ω
C.
 7 Ω
D.
 10 Ω

Explanation:

When steady state is reached with s open, capacitor will act as open circuit

Current in 4Ω resistor will be = 6A at steady state.

Voltage across 4Ω = 6 x 4 24 volt.

Current in 2Ω resistor due to 6A 3A current due to 16 V, source.

I = 16/2 8A, this current divide in (2 + 2) Ω is 4Ω resistor current in 2Ω resistor 4A + 3A 7A.

4.

When a function Z(s) having a pole at infinity is realized, we get

A.
 a capacitance in series
B.
 a resistance in series
C.
 an inductance in series
D.
 a resistance or inductance in series

Explanation:

If we divide numerator by denominator we get term sL.

s Therefore the network has inductance in series.

5.

In the circuit shown in figure the inductor current and capacitor voltage are given at a time t. At this instant i is __________ A and is __________ A/sec.

A.
 -5 A, 10 V
B.
 5 A, 50 V
C.
 2.5, 25
D.
 0, ∞

Explanation:

.

6.

For an RC admittance function Y, the slope dY/dσ

A.
 is positive
B.
 is negative
C.
 may be positive or negative
D.
 0

7.

A network has only independent current sources and resistance. If values of all resistors are doubled, the values of node voltages

A.
 will become half
B.
 will remain unchanged
C.
 will become double
D.
 cannot be determined unless circuit configuration and values of resistors are known

8.

Which of the following is/are correct? The circuit shown in the figure.

1. is reciprocal
2. has Z11 = 2, Z22 = 2
3. has Z11 = 4, Z22 = 2
4. has Z11 = 0, Z22 = 2
Select the correct answer using the code given below:

A.
 1 and 3
B.
 1 and 2
C.
 1 and 4
D.
 3 only

9.

Force = Electric intensity x current.

A.
 True
B.
 False

10.

Which is correct for a transfer function?

A.
 The poles and zero must be complex
B.
 If the poles and zeros are complex or imaginary, they must be conjugate
C.
 If the poles and zeros are complex they must be simple
D.
 If a zero is imaginary, it must be simple

11.

Which one of the following functions is RC driving point impedance?

A.
B.
C.
D.

12.

Consider the following statements regarding driving point admittance function

1. It is an admittance of R1 network
2. Poles and zeros alternate on the negative real axis of plane
3. The lowest critical frequency is a pole
4. Y(0) = 1/3
Which of these statements are correct?

A.
 1, 2 and 3
B.
 2 and 4
C.
 1 and 3
D.
 1, 2, 3 and 4

13.

The two port networks are connected in cascade, the combination is to be represented as a single two-Port network. The parameters of the network are obtained by multiplying the individual matrix

A.
 z-parameter
B.
 h-parameter
C.
 y-parameter
D.
 ABCD parameter

14.

At very low temperatures, semiconducting materials behave as insulators.

A.
 True
B.
 False

15.

A nickel cadmium cell is an alkaline cell.

A.
 True
B.
 False

16.

Current in a 2H inductance in 10e-t A. Admittance of the inductor is

A.
 -0.5 mho
B.
 0.5 mho
C.
 5 mho
D.
 10 mho

17.

The flux linkage ψ, self inductance L and current i are related as

A.
 ψ = L/i
B.
 ψ = Li
C.
 ψ = Li2
D.

18.

In liquids charge carriers are electrons only.

A.
 True
B.
 False

19.

For a transfer function H(s) = P(s)/Q(s), where P(s) and Q(s) are polynomials in s

A.
 the degrees of P(s) is always greater than degree of Q(s)
B.
 the degree of P(s) and Q(s) are equal
C.
 the degree of P(s) is independent of degree of Q(s)
D.
 the maximum difference in degrees of P(s) and Q(s) is 1

20.

A function f(t) = k eat is __________ for (a > 0).

A.
 stable
B.
 unstable
C.
 marginal
D.
 none