Electronics Engineering - Online Test
Q1. 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
Q2. The digital logic shown in the figure satisfies the given state diagram when Q1 is
connected to input A of the XOR gate.
Suppose the XOR gate is replaced by an XNOR gate. Which one of the following
options preserves the state diagram ?
Answer : Option D
Explaination / Solution:
No Explaination.
Q3. A system is defined by its impulse response 
The system is
The system is
Answer : Option B
Explaination / Solution:
No Explaination.
Q4. The propagation constant of a lossy transmission line is (2 + 𝑗5) m-1 and its characteristic impedance is (50 + j0)𝜔 at 𝜔 = 106 rad s-1. The values of the line constants L, C, R, G are, respectively,
Answer : Option B
Explaination / Solution:
Q5. Which one of the following options correctly describes the locations of the roots of the equation s4 + s2 + 1 = 0 on the complex plane?
Answer : Option C
Explaination / Solution:
Hence two roots contain RHS and two roots contain LHS plane.
Q6. 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
Q7.
If segments a to g are considered as functions of P1 and P2, then which of the following is correct
Answer : Option B
Explaination / Solution:
LED d is 1 all condition and also it depends on
d = c + e
Q8.
Assuming zero initial condition, the response y(t) of the system given below to a unit step input u(t) h is
Answer : Option B
Explaination / Solution:
The Laplace transform of unit step fun n is 
U(s)=1/s
So, the O/P of the system is given as
For zero initial condition, we check
Hence, the O/P is correct which is
its inverse Laplace transform is given by
Y(t)=tu(t)
Q9. An antenna pointing in a certain direction has a noise temperature of 50K. The ambient
temperature is 290 K. The antenna is connected to a pre-amplifier that has a noise figure of 2
dB and an available gain of 40 dB over an effective bandwidth of 12 MHz. The effective input
noise temperature Te for the amplifier and the noise power Pao at the output of the preamplifier,
respectively, are
Answer : Option A
Explaination / Solution:
No Explaination.
Q10. The Nyquist plot of the transfer function
does not encircle the point (1+ j0) for K = 10 but does encircle the point (-1+ j0) for K = 100. Then the closed loop system (having unity gain feedback) is
Answer : Option B
Explaination / Solution:
