EC GATE 2011 - Online Test

Q1. In the circuit shown below, the Norton equivalent current in amperes with respect to the terminals P and Q is

Answer : Option A
Explaination / Solution:

Replacing P - Q by short circuit as shown below we have
Using current divider rule the current ISC is



Q2. Two D flip-flops are connected as a synchronous counter that goes through the following QBQsequence 00⟶11⟶01⟶10⟶00⟶… The combination to the inputs DA and DB are
Answer : Option D
Explaination / Solution:

The sequence is QBQA
00⟶11⟶01⟶10⟶00⟶…




Q3. In the circuit shown below, the value of RL such that the power transferred to RL is maximum is

Answer : Option C
Explaination / Solution:

Power transferred to RL will be maximum when RL is equal to the thevenin resistance. We determine thevenin resistance by killing all source as follows :


Q4. An 8085 assembly language program is given below. Assume that the carry flag is initially unset. The content of the accumulator after the execution of the program is

Answer : Option C
Explaination / Solution:

Initially Carry Flag, C = 0 MVI A, 07 H ; A = 0000 0111 RLC ; Rotate left without carry. A = 00001110 MVO B, A ; B = A = 00001110 RLC ; A = 00011100 RLC ; A = 00111000 ADD B ; A = 00111000 ; +00001110 ; 01000110 RRC ; Rotate Right with out carry, A = 0010 0011 Thus A = 23 H

Q5. In the circuit shown below, the current I is equal to 

Answer : Option B
Explaination / Solution:

From star delta conversion we have

Replacing in circuit we have the circuit shown below :

Now the total impedance of circuit is


Q6. The first six points of the 8-point DFT of a real valued sequence are 5, 1 - j3, 0, 3 - 4j, 0 and 3 + 4j .....The last two points of the DFT are respectively
Answer : Option B
Explaination / Solution:

For 8 point DFT,  and it is conjugate symmetric about x[4], x[6] = 0; x[7] = 1 + j3

Q7. In the circuit shown below, the initial charge on the capacitor is 2.5 mC, with the voltage polarity as indicated. The switch is closed at time t = 0. The current i(t) at a time t after the switch is closed is

Answer : Option A
Explaination / Solution:

Here we take the current flow direction as positive.


Q8. 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.

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. For the transfer function G(j𝜔) = 5 + j𝜔, the corresponding Nyquist plot for positive frequency has the form
Answer : Option A
Explaination / Solution:

G(j𝜔) = 5 + j𝜔 Here σ = 5. Thus G(j𝜔) is a straight line parallel to j𝜔 axis