Testbook Logo
Exams SuperCoaching Test Series Skill Academy
More
English
Hindi

Question

Download Solution PDF

Which one of the following statements regarding ‘Root locus’ is not correct?

This question was previously asked in
ESE Electrical 2020: Official Paper
Attempt Online
View all UPSC IES Papers >
  1. By the addition of poles to the left half, the root locus shifts towards the right-hand side, and the stability of the system decreases
  2. By addition of zero towards left, the root locus shifts towards left half, since root locus shifts towards left half, the relative stability of control system increases
  3. By the addition of zero towards the left side, the root locus shifts towards the left half, the relative stability remains the same
  4. By addition of poles to the left half, the system stability decreases, while by addition of zeros towards left half, the stability of system increases

Answer (Detailed Solution Below)

Option 3 : By the addition of zero towards the left side, the root locus shifts towards the left half, the relative stability remains the same
Free Tests
View all Free tests >
Free
ST 1: UPSC ESE (IES) Civil - Building Materials
6.5 K Users
20 Questions 40 Marks 24 Mins
Start Now

Detailed Solution

Download Solution PDF

Effect of addition of zero to the system:

  • The angle of asymptotes increases and this root locus shift towards the left side of the s-plane slightly more
  • Breakaway point shifts towards the left in the s plane
  • The system becomes more stable i.e. less oscillatory
  • The range of ‘K’ value of stability increases
  • The relative stability increases

 

Effect of addition of pole to the system:

  • The angle of asymptotes decreases and this root locus shift towards the right side of the s-plane slightly more
  • Breakaway point shifts towards the right in the s plane
  • The system becomes less stable i.e. more oscillatory
  • The range of ‘K’ value of stability decreases
  • The relative stability decreases
Download Solution PDF
Latest UPSC IES Updates

Last updated on Jul 2, 2025

-> ESE Mains 2025 exam date has been released. As per the schedule, UPSC IES Mains exam 2025 will be conducted on August 10. 

-> UPSC ESE result 2025 has been released. Candidates can download the ESE prelims result PDF from here.

->  UPSC ESE admit card 2025 for the prelims exam has been released. 

-> The UPSC IES Prelims 2025 will be held on 8th June 2025.

-> The selection process includes a Prelims and a Mains Examination, followed by a Personality Test/Interview.

-> Candidates should attempt the UPSC IES mock tests to increase their efficiency. The UPSC IES previous year papers can be downloaded here.

More Root Locus Diagram Questions

Q1.The loop transfer function of a closed-loop control system is given as : \(G(s) H(s)=\frac{k(s+1)}{s(s+2)(s+3)}\) The centroid of the asymptotes in root locus is :
Q2.Root locus always starts from:
Q3.For the unity feedback system with the open loop transfer function G(s) = \(\frac{K}{s(s+1)(s+2)}\), the centroid of root locus is at:
Q4.The breakaway point of the root from the real axis for a closed loop system with a loop gain G(s)H(s) = \(\frac{K(s+10)}{(s+2)(s+5)}\) lies:
Q5.Consider the control system which has a root locus plot as given. The open loop transfer function is given by:
Q6.For the unity feedback system with the open loop transfer function G(s) = \(\frac{K}{s(s+1)(s+2)}\), the number of valid branches of root locus is equal to:
Q7.Consider the control system which has root locus plot as given. The open loop transfer function is given by:
Q8.Consider the control system which has root locus plot as given. The open loop transfer function is:
Q9.Consider the root locus of a unity feedback system which has open loop poles at s = −4, −6, −8 and open loop zeros at s = −5, −7 The angle contribution at point s = −7.5 is:
Q10.A feedback control system has an open-loop transfer function as - G(s).H(s) = \(\frac{k}{s(s+3)(s^{2}+2 s+2)}\) Find the centroid.
Suggested Test Series
View All >
UPSC ESE (IES) Civil Mock Test Series
116 Total Tests with 1 Free Tests
Start Free Test
UPSC ESE (IES) Electrical Mock Test Series
68 Total Tests with   0 Free Tests
Start Free Test
Suggested Exams
Exam-Logo
RCFL

RCFL Important Links

More Control Systems Questions

Q1.A unity feedback system is characterized by the open-loop transfer function \(G(s)=\frac{100}{s(5 s+10)(2 s+10)}\) The steady-state errors for unit-step and unit-ramp inputs are :
Q2.In the circuit shown switch is closed at t = 0. The time constant of the circuit is :
Q3.The loop transfer function of a closed-loop control system is given as : \(G(s) H(s)=\frac{k(s+1)}{s(s+2)(s+3)}\) The centroid of the asymptotes in root locus is :
Q4.For a control system having fourteen poles and two zeros, the slope in its magnitude plot for high frequency asymptote will be :
Q5.The Routh Array is as below : \(\begin{array}{lllll} \mathrm{S}^{6} & 1 & 8 & 20 & 16 \\ \mathrm{S}^{5} & 2 & 12 & 16 & \\ \mathrm{S}^{4} & 2 & 12 & 16 & \\ \mathrm{S}^{3} & 0 & 0 & & \end{array}\) The row of zero of this array will be replaced by coefficients of 
Q6.The number of roots in the left half of the s-plane for a system having characteristic equations : s3 + 5s2 + 7s + 3 = 0 is : 
Q7.Explain the pattern and trend of public expenditure on social services in the post reforms period in India. To what extent this has been in consonance with achieving objective of inclusive growth? 
Q8.The Nyquist criterion for stability states that an amplifier is unstable if the Nyquist curve encloses the -1 + j0 point, and the amplifier is stable if the curve does not enclose this point. If Aβ
Q9.The phase margin of a system with the open-loop transfer function \(G(s) H(s)=\frac{1-s}{(s+1)(s+2)}\) is
Q10.The phase margin of a system having the loop transfer function \(G(s) H(s)=\frac{2 \sqrt{3}}{s(s+1)}\) is
Exams
Test Series
SuperCoaching
Previous Year Papers
Latest Updates
MCQ Questions
Testbook Products & Resources for Students
Testbook USA
Books
Testbook Edu Solutions Pvt. Ltd.
1st & 2nd Floor, Zion Building,
Plot No. 273, Sector 10, Kharghar,
Navi Mumbai - 410210
[email protected]
Toll Free:1800 833 0800
Office Hours: 10 AM to 7 PM (all 7 days)
Company
About usCareers We are hiringTeach Online on TestbookPartnersMediaSitemap
Products
Test SeriesTestbook PassOnline CoursesOnline VideosPracticeBlogRefer & EarnBooks
Our Apps
Follow us on
Copyright © 2014-2022 Testbook Edu Solutions Pvt. Ltd.: All rights reserved
User PolicyTermsPrivacy
Get Free Access Now
Hot Links： teen patti all app teen patti master teen patti bindaas