Electronics Engineering - Online Test
Q1. A white noise process X(t) with two-sided power spectral density 1 X 10-10 W/HZ is input to a filter whose magnitude squared response is shown below.
Answer : Option C
Explaination / Solution:
No Explaination.
Q2.
Compared to a p-n junction with NA = ND = 10-14/cm3, which one of the following statements is TRUE for a p-n junction with NA = ND = 10-20/cm3?
Answer : Option C
Explaination / Solution:
Reverse bias breakdown or Zener effect occurs in highly doped PN junction through tunneling mechanism. In a highly doped PN junction, the conduction and valence bands on opposite sides of the junction are sufficiently close during reverse bias that electron may tunnel directly from the valence band on the p-side into the conduction band on n-side.
Breakdown voltage 
So, breakdown voltage decreases as concentration increases
Depletion capacitance
Depletion capacitance increases as concentration increases
Q3. The following Karnaugh map represent a function F.
Which of the following circuits is a realization of the above function F?
Answer : Option D
Explaination / Solution:
No Explaination.
Q4. Transformer and emitter follower can both be used for impedance matching at the output of an audio amplifier. The basic relationship between the input power Pin and output power Pout in both the cases is
Answer : Option A
Explaination / Solution:
No Explaination.
Q5. A series RL circuit is excited at t = 0 by closing a switch as shown in the figure.
Assuming zero initial conditions, the value of 
is
is
Answer : Option D
Explaination / Solution:
Q6. In the ac equivalent circuit shown in the figure, if iin is the input current and Rf is very larger, the type of feedback is
Answer : Option B
Explaination / Solution:
From the circuit, we observe that output is Vout (Voltage). Feedback is current
through resistance Rf , which is added to input current iin . Thus, the configuration
is voltage-current feedback.
Q7. Let x1(t) ↔ X1(ω) and x2(t) ↔ X2(ω) be two signals whose Fourier Transforms are as shown in the figure below. In the figure, h(t) = e-2|t| denotes the impulse response.
For the system shown above, the minimum sampling rate required to sample y(t), so that y(t) can be uniquely reconstructed from its samples, is
Answer : Option B
Explaination / Solution:
Q8. Consider a linear time invariant system x = Ax, with initial condition x(0) at t = 0. Suppose α and β are eigenvectors of (2 x 2) matrix A corresponding to distinct eigenvalues λ1 and λ2 respectively.
Then the response x(t) of the system due to initial condition x(0) = α is
Answer : Option A
Explaination / Solution:
Q9. The divergence of the vector field 
Answer : Option D
Explaination / Solution:
Given, the vector field
Q10. The signal 
is
is
Answer : Option C
Explaination / Solution:
No Explaination.
