# The gain margin of a system is 0 dB. It represents a

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The gain margin of a system is 0 dB. It represents a

(a) Stable system (b) Unstable system (c) Marginally stable system (d) Conditionally stable system

The gain margin of a system is 0 dB. It represents a Marginally stable system

## Related questions

A unity negative feedback control system is found to have a gain margin of 20 dB. The Nyquist plot of the system (A) crosses the real axis at +0.1 (B) crosses the real axis at -0.1. (C) crosses the imaginary axis at -0.1 (D) crosses the imaginary axis at +0.1

What will happen to the gain margin if the gain of the open loop system is doubled? A) Doubled B) Becomes half C) Is not affected D) Becomes one-fourth

If the gain of the open loop system is doubled, the gain margin  (1) Is not affected (2) Gets doubled (3) Becomes half (4) Becomes one -forth

A system with gain margin close to unity or a phase margin close to zero is (a) conditionally stable (b) relatively stable (c) highly stable (d) highly oscillatory

The characteristic equation for a closed loop system with forward gain K is s4 + 4s3 + 8s2 + 6s + K = 0. The critical gain value Kc for stability should not exceed  (a) 3.25 (b) 9.75 (c) 13.0 (d) 23.3

If the gain of the critical damped system is increased it will behave as?

If Ф = angle(G(jw)H(jw)) where w is the gain crossover frequency of Bode plot of the system, phase margin is  A) -180+ Ф B) 180- Ф C) 180+ Ф D) -180- Ф

For better relative stability, the values of gain margin and phase margin should be respectively  A) 6 db, 15 degree B) 10 db, 15 degree C) 10 db, 30 degree D) 6 db, 30 degree

For a stable feedback control system, the phase margin is  a) always positive b) always negative c) may be positive or negative d) always greater than 180o

Phase margin is the amount of angle to make the system  (1) Oscillatory (2) Stable (3) Unstable (4) Exponential

The unit circle of the Nyquist plot transforms into unity or 0 dB line of the amplitude plot of the Bode diagram for

A system is critically damped. If the gain of the system is increased, the system will behave as: A) overdamped B) underdamped C) oscillatory D) critically damped

Given a unity feedback system with G(s)=k/s (s+4), the value of k for damping ratio of 0.5 is

By increasing the gain ‘k’ of a system, steady state error of the system (a) increases (b) decreases (c) remains unaffected (d) nothing can be said

The sensitivity of a closed loop system to gain changes and load disturbances depends upon (a) forward gain (b) loop gain (c) frequency (d) all the above

In the Bode plot of a unity feedback control system, the value of phase of G(jw) at the gain cross -over frequency is - 125°.. The phase margin of the system is (a) - 125° (b) - 55° (c) 55° (d) 125°

A differential amplifier has a differential gain of 28000 and CMRR is 60 dB. What will be the value of common mode gain? A) Ac = 0.125 B) Ac = 0.33 C) Ac = 3 D) Ac = 28

A differential amplifier has a differential gain of 20,000, CMRR : 80 dB. The common mode gain is given by

The RF amplifier A is having 3 dB NF & 5 dB of gain, amplifier B is having 3.5 dB NF & 15 dB . For overall noise figure of the cascaded system, the correct statement is :  a. A as first stage & B as second stage offers minimum over all NF b. B as first stage & A as second stage minimum over all NF c. Both the combination will offer same overall NF d. Over all NF will be less than 3 dB.

When the initial conditions of a system are specified to be zero it implies that the system is?

The dc gain of the system represented by the transfer function G(s)=(s+6)/((s+2)(s+3)) is  A) 1 B) 2 C) 5 D) 6

For a 2nd order servo system, the damping ratio δ = 0.5456 and undamped natural frequency is ωn = 31.6 rad/sec. The percent overshoot is  (a) 7.07 (b) 10.2 (c) 14.10 (d) 21.21

What is the steady state error of type-0 system for ramp input?  A) ∞ B) A/K C) A/(1+K) D) 0

In closed loop control system, with positive value of feedback gain the overall gain of the system will

An amplifier has input power of 2 microwatts. The power gain of the amplifier is 60 dB. The output power will be

An amplifier has a voltage gain of 50; this gain in dB will be (A) 34 dB (B) 68 dB (C) 41 dB (D) 14 dB

A dominant pole compensated op-amp has openloop gain of 100 dB and -3 dB bandwidth of 50 Hz. If it is connected as inverting amplifier for a gain of 20 dB the -3 dB bandwidth is about  A) 500 kHz B) 50 kHz C) 5 kHz D) 500 Hz

A system is linear if and only if it satisfies

A differentiator is not usually used in control system, because it : - (A) reduces damping  (B) increases error  (C) reduces gain margin  (D) increases input noise

A system has transfer function (1–s) ÷ (1+s). It is  A) Non minimum phase transfer function B) Minimum phase transfer function C) Low pass system D) Second order system

With negative feedback, the system stability and system gain respectively (a) Increases and increases (b) Increases and decreases (c) Decreases and increases (d) Decreases and decreases

An amplifier without feedback has a gain of 1000. The gain with a negative feedback of 0.009 is  A) 10 B) 100 C) 125 D) 900

A second order system shows 100% overshoot in its unit step response. It can be categorized as (A) underdamped system. (B) overdamped system. (C) Critically damped system. (D) undamped system.

The type 0 system has ______ at the origin.

The unity circle of Nyquist plot corresponds to zero dB line of Bode plot for  A) High frequencies B) Low frequencies C) Medium frequencies D) All frequencies

What is the number of turns of wire needed to provide a potentiometer with a resolution of 0.05 percent ? (a) 200 turns (b) 2000 turns (c) 20 turns (d) 20000 turns

In a differential amplifier the differential voltage gain is 500 and the common mode voltage gain is 0.5. The CMRR in dB is (a) 80 (b) 60 (c) 30 (d) 20

After drawing the Root-Locus, the closed-loop poles corresponding to a specified value of gain K can be determined from which of the following criterion ? (A) Magnitude criterion alone (B) Angle criterion alone (C) Both Magnitude and Angle criteria (D) Angle of departure and angle of arrival.

If the feedback factor of an amplifier is 0.1 and its gain without feedback is 40, then its gain with feedback is (a) – 13.3 (b) 200 (c) 8 (d) 10

An OP amp has an open loop gain of 1,00,000. If the feedback fraction is 0.02, the approximate closed loop gain is (a) 1 (b) 1,00,000 (c) 50 (d) 0.02

The characteristic equation of a simple servo system is s2+6s+25=0. Damping factor of the system is: A) 3.2 B) 2.4 C) 1.8 D) 2.9

The corona loss in a 50 Hz system is 0.25 kW/ph/km. At a frequency of 60 Hz, the corona loss would be   (a) 0.30 kW/ph/km (b) 0.36 kW/ph/km (c) 028 kW/ph/km (d) 0.21 kW/ph/km

If the characteristics equation of a closed loop system is s2+2s+2=0, then the system is  (A) Over damped (B) Critically damped (C) Under damped (D) Undamped

What is the time response of a system whose poles lie on the right hand side of s-plane? A) Exponentially increasing B) Exponentially decreasing C) Sinusoidal oscillations D) Step response

The best method for determining the stability and transient response of a control system is (a) Bode Plot (b) Nyquist plot (c) Root locus (d) Routh-Hurwitz