Nyquist Plot Question & Answers October 7, 2022 By WatElectronics This article lists 40 Nyquist Plot MCQs for engineering students. All the Nyquist Plot Questions & Answers given below include a hint and a link wherever possible to the relevant topic. This is helpful for users who are preparing for their exams, interviews, or professionals who would like to brush up on the fundamentals of Nyquist Plot. Harry Nyquist an engineer at Bell Laboratories discovered the ‘Nyquist plot’. This plot is a continuation of Polar plots. To find closed loops control system stability by changing omega (ω) i.e., from -∞ to + ∞. Complete response of frequency is obtained of open loop transfer functions using this plot. The criterion of Nyquist stability is based on the 'Principle of argument'. If poles and zeroes are presently enclosed in a path close to plane S, then G(s) H(s) corresponding plane must be encircled origin with times P-Z. Hence the encirclements can be written as N is P-Z. The selected enclosed path of a Nyquist plane is referred to as Nyquist Contour. All the poles if lying in the s-planes left halve make the closed loops control system stable. Critical point lying encirclements outside indicates the absolute stability of closed-loop control systems. Cross-over frequencies of phase and gain also their margins that are used in finding out whether the systems are stable or not are determined using the Nyquist plot. Control engineering and the processing of signals use this response of frequency known as a Nyquist plot. 1). _______ used in determining the stability of the control system? Bode Plot Nyquist Plot Polar Plot Root Locus Hint 2). ___________ plots are continued from Polar plots? Bode Plot Nyquist Plot Nicholes Plot Root Locus Hint 3). On what principle Nyquist stability is based? Principle of Reflection Principle of Argument Principle of Refraction Principle of Total Internal Reflection Hint 4). How many encirclements are enclosed if a path is closed? N = P N = Z N = P-Z N= PZ Hint 5). What if the enclosed path consists of poles but not zeroes then the direction encircled is? Opposite in Direction of Enclosed Closed Path Same in Direction of Enclosed Closed Path Encircling is Impossible Both Poles and Zeroes are Required Hint 6). The path selected based on Principle of Argument is in a Nyquist plot is _________? Nyquist Area Nyquist Region Nyquist Contour Nyquist Centre Hint 7). Poles present on left-half of plane S of a Closed-loop Transfer function indicates ________? Closed Loop Control System is Stable Closed Loop Control System is Partially Stable Closed Loop Control System is Unstable None Hint 8). What is known as the roots of a Characteristic equation? Poles Zeroes Origin Critical Point Hint 9). Poles of a Characteristic equation are similar to poles of a ____________ Transfer function? Open Loop Closed Loop Origin Plane Hint 10). A Nyquist plot doesn't contain any pole of open-loop on the right side of plane S then N is equivalent to ___________? N = P N = -Z N = P-Z N= PZ Hint Nyquist Plot MCQs for Exams 11). What if there are no closed-loop poles on the right side of the S-plane in a Nyquist plot? N = P N = -Z N = P-Z N= PZ Hint 12). Number of encircles at a Critical point must equivalent to ___________? Poles of Characteristic Equation Poles of Open Loop Transfer Function Poles of Closed Loop Transfer Function a & b Hint 13). Frequency where the Nyquist plots intersect negative part of Real axis is referred to as ____________? Gain Margin Phase Cross-Over Frequency Phase Margin Gain Cross-Over Frequency Hint 14). Nyquist plots have magnitude as one at a certain frequency referred to as ____________? Gain Margin Phase Cross-Over Frequency Phase Margin Gain Cross-Over Frequency Hint 15). Control system gets stable if? Phase Cross Over Frequency > Gain Cross Over Frequency Phase Cross Over Frequency = Gain Cross Over Frequency Phase Cross Over Frequency < Gain Cross Over Frequency Phase Cross Over Frequency ≥ Gain Cross Over Frequency Hint 16). If Phase Cross Over Frequency = Gain Cross Over Frequency indicates the system? Stable Marginally Stable Unstable None Hint 17). What is the reciprocal of Nyquist plots magnitude? Gain Margin Phase Cross-Over Frequency Phase Margin Gain Cross-Over Frequency Hint 18). Phase Margin is equivalent to ___________? 180 + Phase Angle 180 + Gain 90 + Phase Angle Phase Angle + Gain Hint 19). Based on margins how do the control systems indicate stability? GM > 1 PM is Negative GM< 1 a & b Hint 20). Control systems are marginally stable if the Gain margin is _______? GM > 1 GM < 1 GM = 1 GM = 0 Hint Nyquist Plot MCQs for Students 21). If gain margin is lesser than one indicates system is __________? Stable Marginally Stable Unstable None Hint 22). How does the frequency in the Nyquist plot get varied? -∞ to 0 0 to +∞ -∞ to + ∞ Zero Hint 23). What is the basic difference between polar and Nyquist plots? Number of poles Number of Zeroes Frequency Handled a & b Hint 24). ________ combines phase and gain in a single plot of complex planes? Bode Plot Nyquist Plot Nicholes Plot Polar Plot Hint 25). How the Nyquist plots are described in the cartesian system of coordinates? Real Part Plot on X-axis Real Part Plot on Y-Axis Imaginary Part Plot on X-Axis a & b Hint 26). How Nyquist plot described based on Polar coordinates? Gain Represented on Radial Coordinate Phase Represented on Angular Coordinate Phase Represented on Radial Coordinate a & b Hint 27). What are the plots that determine the Relative stability of systems? Bode Plot Nyquist Plot Nicholes Plot a & b Hint 28). Closed contour present on plane S that enclose entire RHS referred to as _________? Nyquist Path Nyquist Origin Nyquist Circle Nyquist Encircle Hint 29). Radius of the semi-circle on the Nyquist plot is referred to as ________? Nyquist Path Nyquist Origin Nyquist Circle Nyquist Encirclement Hint 30). Process of transforming point present in plane S into F(s) referred to as _________? Nyquist Path Nyquist Mapping Nyquist Circle Nyquist Encirclement Hint Nyquist Plot MCQs for Quiz 31). Interconnection of all mapped distinct segments yields the needed _________? Nyquist Path Nyquist Mapping Nyquist Diagram Nyquist Encirclement Hint 32). What is required in preserving the information of signals? Nyquist Path Nyquist Mapping Nyquist Diagram Nyquist Frequency Hint 33). What is the radius size for any Nyquist Contour? 0 1 100 ∞ Hint 34). What is the point where the Nyquist plots pass considering the system as stable? -1 0 1 ∞ Hint 35). Contour gets encircled to point -1 indicates the system as ________? Stable Marginally Stable Unstable None Hint 36). Nyquist plot finds _________ of an Open-loop Transfer function? Poles Zeroes Frequency Response All Mentioned Above Hint 37). What doesn't provide exact information on poles? Bode Plot Nyquist Plot Nicholes Plot Polar Plot Hint 38). Nyquist plot use _________ Mathematical techniques? Simple Easier Complex Uncomplicated Hint 39). What is better compared to Root locus? Bode Plot Nyquist Plot Nicholes Plot Polar Plot Hint 40). What is utilized in drawing a complete response of frequency for an Open-loop Transfer function? Bode Plot Nyquist Plot Nicholes Plot Polar Plot Hint Please fill in the comment box below. Time's up