Electrical Engineering - Online Test
Q1.
Which one of the following statements is NOT TRUE for a continuous time causal and stable LTI system?
Answer : Option C
Explaination / Solution:
For a system to be casual, the R.O.C of system transfer function H(s) h which is rational should be in the right half plane and to the right of the right most pole.
For the stability of LTI system. All poles of the system should lie in the left half of S -plane and no repeated pole should be on imaginary axis. Hence,
options (A), (B), (D) satisfies an LTI system stability and causality both.
But, Option (C) is not true for the stable system as, ƖsƖ =1 have one pole in right hand plane also.
Q2. 
Answer : Option C
Explaination / Solution:
We have
Q3. The DFT of a vector [a b c d] is the vector [α β γ δ]. Consider the product 
The DFT of the vector [p q r s] is a scaled version of
Answer : Option A
Explaination / Solution:
No Explaination.
Q4. A voltage 1000 sin𝜔t Volts is applied across YZ . Assuming ideal diodes, the
voltage measured across WX in Volts, is
Answer : Option D
Explaination / Solution:
No Explaination.
Q5. An analog signal is band-limited to 4 kHz, sampled at the Nyquist rate and the samples are quantized into 4 levels. The quantized levels are assumed to be independent and equally probable. If we transmit two quantized samples per second, the information rate is ________ bits / second.
Answer : Option D
Explaination / Solution:
Quantized 4 level require 2 bit representation i.e. for one sample 2 bit are required. Since 2 sample per second are transmitted we require 4 bit to be transmitted per second.
Q6. Consider the system
where p and q are arbitrary real numbers. Which of the following statements about the controllability of the system is true ?
Answer : Option C
Explaination / Solution:
Since S is singular, system is completely uncontrollable for all values of p and q .
Q7. In the circuit shown below, Q1 has negligible collector-to-emitter saturation voltage and the diode drops negligible voltage across it under forward bias. If Vcc is +5 V, X and Y are digital signals with 0 V as logic 0 and Vcc as logic 1,
then the Boolean expression for Z is
Answer : Option B
Explaination / Solution:
No Explaination.
Q8. Three capacitors C1, C2 and C3 whose values are 10 μF , 5 μF , and 2 μF respectively, have breakdown voltages of 10 V, 5 V and 2 V respectively. For the
interconnection shown below, the maximum safe voltage in Volts that can be
applied across the combination, and the corresponding total charge in μC stored
in the effective capacitance across the terminals are respectively
Answer : Option C
Explaination / Solution:
No Explaination.
Q9. The root locus plot for a system is given below. The open loop transfer function
corresponding to this plot is given by
Answer : Option B
Explaination / Solution:
For given plot root locus exists from -3 to ∞, So there must be odd number of
poles and zeros. There is a double pole at s = - 3
Now poles = 0, -2, -3, -3
zeros = - 1
Thus transfer function 
Q10. Consider two independent random variables X and Y with identical distributions. The variables X and Y take values 0, 1 and 2 with probabilities 1/2,1/4 and 1/4 respectively. What is the conditional probability P(X + Y = 2 X - Y = 0) ?
Answer : Option C
Explaination / Solution:
We have
