Electrical Engineering - Online Test
Q1. The output of a 3-stage Johnson (twisted ring) counter is fed to a digital-to
analog (D/A) converter as shown in the figure below. Assume all the states
of the counter to be unset initially. The waveform which represents the D/A
converter output v0 is
Answer : Option A
Explaination / Solution:
All the states of the counter are initially unset.
State Initially are shown below in table:
Q2Q1Q0
0 0 0 0
1 0 0 4
1 1 0 6
1 1 1 7
0 1 1 3
0 0 1 1
0 0 0 0
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. An LTI system having transfer function 
and input x(t) = sin(t + 1) is in steady state. The output is sampled at a rate ws rad/s to obtain the final output {x(k)}. Which of the following is true ?
and input x(t) = sin(t + 1) is in steady state. The output is sampled at a rate ws rad/s to obtain the final output {x(k)}. Which of the following is true ?
Answer : Option A
Explaination / Solution:
No Explaination.
Q4. 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
Q5. Consider the z -transform 
The inverse z -transform x[n] is
The inverse z -transform x[n] is
Answer : Option A
Explaination / Solution:
Q6. Two D flip-flops are connected as a synchronous counter that goes through the
following QBQA sequence 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⟶…
Q7. The unit step response of an under-damped second order system has steady state value of -2. Which one of the following transfer functions has theses properties ?
Answer : Option B
Explaination / Solution:
For under-damped second order response
Q8. 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 :
Q9. If ey = x1/x , then y has a
Answer : Option A
Explaination / Solution:
Q10. 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
