Root Locus Diagram
Practice Questions
Marks 2
1
A linear time invariant (LTI) system with the transfer function $$$G\left(s\right)=\frac{K\left(s^2+2s+2\right)}{s^2-3s+2}$$$ is connected in unity feedback configuration as shown in the figure. GATE ECE 2017 Set 1 Control Systems - Root Locus Diagram Question 9 English

For the closed loop system shown, the root locus for 0 < K < $$\infty$$ intersects the imaginary axis for K = 1.5. The closed loop system is stable for

GATE ECE 2017 Set 1
2
The forward-path transfer function and the feedback-path transfer function of a single loop negative feedback control system are given as $$G\left(s\right)=\frac{K\left(s+2\right)}{s^2+2s+2}$$ and H(s) = 1 respectively.If the variable parameter K is real positive, then the location of the breakaway point on the root locus diagram of the system is_____________.
GATE ECE 2016 Set 3
3
The open-loop transfer function of a unity-feedback control system is $$$G\left(s\right)=\frac K{s^2+5s+5}$$$ The value of K at the breakaway point of the feedback control system's root-locus plot is _____________
GATE ECE 2016 Set 1
4
For the system shown in the figure, s = –2.75 lies on the root locus if K is_____. GATE ECE 2015 Set 3 Control Systems - Root Locus Diagram Question 12 English
GATE ECE 2015 Set 3
5
The open-loop transfer function of a plant in a unity feedback configuration is given as $$G\left(s\right)=\frac{K\left(s+4\right)}{\left(s+8\right)\left(s^2-9\right)}$$.The value of the gain K(>0) for which -1 + j2 lies on the root locus is __________________.
GATE ECE 2015 Set 1
6
The characteristic equation of a unity negative feedback system 1 + KG(s) = 0. The open loop transfer function G(s) has one pole at 0 and two poles at -1. The root locus of the system for varying K is shown in the figure. GATE ECE 2014 Set 4 Control Systems - Root Locus Diagram Question 14 English

The constant damping ratio line, for $$\xi$$ = 0.5 , intersects the root locus at point A. The distance from the origin to point A is given as 0.5. The value of K at point A is ________ .

GATE ECE 2014 Set 4
7
In the root locus plot shown in the figure, the pole/zero marks and the arrows have been removed. Which one of the following transfer functions has this root locus? GATE ECE 2014 Set 3 Control Systems - Root Locus Diagram Question 3 English
GATE ECE 2014 Set 3
8
A unity feedback control system has an open-loop transfer function $$$G\left(s\right)=\frac K{s\left(s^2+7s+12\right)}$$$ The gain K for which s = −1 + j1 will lie on the root locus of this system is:
GATE ECE 2007
9
A unity feedback system is given as,$$$G\left(s\right)=\frac{K\left(1-s\right)}{s\left(s+3\right)}$$$ indicate the correct root locus diagram.
GATE ECE 2005
10
The root locus of the system $$$G\left(s\right)H\left(s\right)=\frac K{s\left(s+2\right)\left(s+3\right)}$$$ has the break-away point located at
GATE ECE 2003
11
Consider the points s1 = −3 + j4 and s2 = −3 − j2 in the s-plane. Then, for a system with the open loop transfer function $$$G\left(s\right)H\left(s\right)=\frac K{\left(s+1\right)^4}$$$
GATE ECE 1999
12
Given a unity feedback system with open loop transfer function, $$$G\left(s\right)=\frac K{s\left(s+1\right)\left(s+2\right)}$$$ The root locus plot of the system is of the form.
GATE ECE 1992
13
The characteristic equation of a feedback control system is given by
s3 +5s2 +(K + 6)s + K =0
Where K > 0 is a scalar variable parameter. In the root loci diagram of the system the asymptotes of the root locus for large values of K meet at a point in the s-plane whose coordinates are
GATE ECE 1991
14
Consider a closed-loop system shown in fig. (a) below. The root locus for it is shown in fig. (b). The closed-loop transfer function for the system is GATE ECE 1988 Control Systems - Root Locus Diagram Question 6 English
GATE ECE 1988