EC GATE 2013 - Online Test
Q1. A source 
has an internal impedance of 
If a purely resistive load connected to this source has to extract the maximum power out of the source, its value inΩ should be
has an internal impedance of If a purely resistive load connected to this source has to extract the maximum power out of the source, its value inΩ should be
Answer : Option C
Explaination / Solution:
For the purely resistive load, maximum average power is transferred when
where
is the equivalent thevinin (input) impedance of the circuit. Hence,
we obtain
where
is the equivalent thevinin (input) impedance of the circuit. Hence,we obtain
Q2. The impulse response of a continuous time system is given by 
The value of the step response at t = 2 is
The value of the step response at t = 2 is
Answer : Option B
Explaination / Solution:
Q3. The Bode plot of a transfer function G(s) h is shown in the figure below.
The gain (20 log ƖG(S)Ɩ) is 32 dB and -8 dB at 1 rad/s and 10 rad/s respectively The phase is negative for all ω Then G(S) is
Answer : Option B
Explaination / Solution:
From the given plot, we obtain the slope as
Q4. In the circuit shown below, if the source voltage 
then the
Thevenin’s equivalent voltage in Volts as seen by the load resistance RL is
then the
Thevenin’s equivalent voltage in Volts as seen by the load resistance RL is
Answer : Option C
Explaination / Solution:
No Explaination.
Q5.
In a voltage-voltage feedback as shown below, which one of the following statements is TRUE if the gain k is increased?
Answer : Option A
Explaination / Solution:
The i/p voltage of the system is given as
Therefore, if k is increased then input voltage is also increased so, the input impedance increases. Now, we have
Since, Vin is independent of k when seen from output mode, the output voltage decreases with increase in k that leads to the decrease of output impedance. Thus, input impedance increases and output impedance decreases.
Q6. The following arrangement consists of an ideal transformer and an attenuator
which attenuates by a factor of 0.8. An ac voltage VWXI = 100 V is applied
across WX to get an open circuit voltage VYZ1 across YZ. Next, an ac voltage VYZ2 = 100 V is applied across YZ to get an open circuit voltage VWX2 across
WX. Then, VYZI/VWX1, VWX2/VYZ2 are respectively.
Answer : Option C
Explaination / Solution:
Q7.
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.
Q8. 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.
Q9. 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.
Q10. 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.
