Control Systems Questions and Answers – Block diagram Algebra

This set of Control Systems Multiple Choice Questions & Answers (MCQs) focuses on “Block diagram Algebra”.

1. Consider the block diagram shown below:
X is G2G4 if transfer function of system is given by T(s)=G1G2+G2G3/1+X
If the transfer function of the system is given by T(s)=G1G2+G2G3/1+X. Then X is:
a) G2G3G4
b) G2G4
c) G1G2G4
d) G3G4
View Answer

Answer: b
Explanation: Use the technique of making two different block diagram by dividing two summers and use the approaches of shifting take off point and blocks.

2. For the block diagram given in the following figure, the expression of C/R is:
The expression of C/R is G1G2G3/1-G2G1 in the block diagram
a) G1G2G3/1-G2G1
b) G1G2/1-G1G2G3
c) G1G2G3/1-G1G2G3
d) G1G2/G3(1-G1G2)
View Answer

Answer: a
Explanation: Block diagram is being converted into signal flow graphs by considering each take off point as a node and each forward transfer function as forward gain.

3. The transfer function from D(s) to Y(s) is :
The transfer function from D(s) to Y(s) is 2/3s+7
a) 2/3s+7
b) 2/3s+1
c) 6/3s+7
d) 2/3s+6
View Answer

Answer: a
Explanation: Y(s)/D(s) = G(s)/(1+G(s)H(s) where G(s) = 2/3s+1 and H(s) = 3
Y(s)/D(s) = 2/3s+1/1+3*(2/3s+1) = 2/3s+7.
advertisement
advertisement

4. The closed loop gain of the system shown in the given figure is :
The closed loop gain of the system shown in the given figure is -6/5
a) -9/5
b) -6/5
c) 6/5
d) 9/5
View Answer

Answer: b
Explanation: C(s)/R(s) = G(s)/(1+G(s)H(s)) where G(s) = -3 and H(s) = 0.5
C(s)/R(s) = -3/1 + 3/2 = -6/5.
=-6/5.

5. The advantage of block diagram representation is that it is possible to evaluate the contribution of each component to the overall performance of the system.
a) True
b) False
View Answer

Answer: a
Explanation: The advantage of the block diagram is that it is possible to get the contribution of each block to the overall performance of the system.
Note: Join free Sanfoundry classes at Telegram or Youtube

6. The overall transfer function from block diagram reduction for cascaded blocks is :
a) Sum of individual gain
b) Product of individual gain
c) Difference of individual gain
d) Division of individual gain
View Answer

Answer: b
Explanation: Gain of block get multiplied when they are cascaded where cascaded means that the blocks are in series combination with no summer in between.

7. The overall transfer function of two blocks in parallel are :
a) Sum of individual gain
b) Product of individual gain
c) Difference of individual gain
d) Division of individual gain
View Answer

Answer: a
Explanation: The gains get added as the blocks are connected in parallel with the summer in between and they are connected with the same sign.
advertisement

8. Transfer function of the system is defined as the ratio of Laplace output to Laplace input considering initial conditions________
a) 1
b) 2
c) 0
d) infinite
View Answer

Answer: c
Explanation: By definition transfer function is the ratio of the laplace output to the input but the initial conditions mainly the stored energy is zero.

9. In the following block diagram, G1=10/s G2=10/s+1 H1=s+3, H2=1. The overall transfer function is given by :
The overall transfer function is 100/11s2+31s+100 in the block diagram
a) 10/11s2+31s+10
b) 100/11s2+31s+100
c) 100/11s2+31s+10
d) 100/11s2+31s
View Answer

Answer: b
Explanation: C/R=G2G1/1+G2H2+G1G2H2
C/R=100/11s2+31s+100.
advertisement

10. Oscillations in output response is due to :
a) Positive feedback
b) Negative feedback
c) No feedback
d) None of the mentioned
View Answer

Answer: a
Explanation: Oscillations are the unwanted sinuoidal signals with high gain in positive feedback and s the damping factor is absent in the positive feedback system entirely oscillations are present.

Sanfoundry Global Education & Learning Series – Control Systems.
To practice all areas of Control Systems, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

advertisement
advertisement
Subscribe to our Newsletters (Subject-wise). Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Join our social networks below and stay updated with latest contests, videos, internships and jobs!

Youtube | Telegram | LinkedIn | Instagram | Facebook | Twitter | Pinterest
Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

Subscribe to his free Masterclasses at Youtube & discussions at Telegram SanfoundryClasses.