# Multiple choice question for engineering

## Set 1

1. A conditionally stable system exhibits poor stability at :

a) Low frequencies

b) Reduced values of open loop gain

c) Increased values of open loop gain

d) High frequencies

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2. The type 0 system has ______ at the origin.

a) No pole

b) Net pole

c) Simple pole

d) Two poles

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3. The type 1 system has ______ at the origin.

a) No pole

b) Net pole

c) Simple pole

d) Two poles

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4. The type 2 system has at the origin.

a) No net pole

b) Net pole

c) Simple pole

d) Two poles

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5. The position and velocity errors of a type-2 system are :

a) Constant, constant

b) Constant, infinity

c) Zero, constant

d) Zero, zero

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6. Velocity error constant of a system is measured when the input to the system is unit _______ function.

a) Parabolic

b) Ramp

c) Impulse

d) Step

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7. In case of type-1 system steady state acceleration is :

a) Unity

b) Infinity

c) Zero

d) 10

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8. If a step function is applied to the input of a system and the output remains below a certain level for all the time, the system is :

a) Not necessarily stable

b) Stable

c) Unstable

d) Always unstable

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9. Which of the following is the best method for determining the stability and transient response?

a) Root locus

b) Bode plot

c) Nyquist plot

d) None of the mentioned

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10. Phase margin of a system is used to specify which of the following?

a) Frequency response

b) Absolute stability

c) Relative

d) Conditional stability

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## Set 2

1. If the performance index of a phase lead compensator is (s+a)/ (s+b) and that of a lag compensator is (s+p)/(s+q), then which one of the following sets of conditions must be satisfied?

a) a>b and p<q

b) a>b and p<q

c) a<b and p<q

d) a<b and p>q

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2. The compensator Gc(s) =5(1+0.3s)/(1+0.1s) would provide a maximum phase shift of:

a) 20°

b) 45°

c) 30°

d) 60°

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^{^}(-1) [(1-α)/(1+α)] and sin

^{^}(-1)[1/2] = 30°.

3. The industrial controller having the best steady-state accuracy is:

a) A derivative controller

b) An integral controller

c) A rate feedback controller

d) A proportional controller

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4. Assertion (A): An on-off controller gives rise to self-sustained oscillation in output.

Reason (R): Location of a pair of poles on the imaginary axis gives to self-sustained oscillation is output.

a) Both A and R true and R is correct explanation of A

b) Both A and R are true but R is not correct explanation of A

c) A is true and R is False

d) A is False and R is True

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5. Consider the following statement:

A proportional plus derivative controller

1. Has high sensitivity

2. Increases the stability of the system

3. Improves the steady state accuracy

Which of these statements are correct?

a) 1,2 and 3

b) 1 and 2

c) 2 and 3

d) 1 and 3

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6. Which one of the following compensation is required for improving the transient response of the system?

a) Phase lead compensation

b) Phase lag compensation

c) Gain compensation

d) Both phase lag compensation and gain compensation

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7. Pneumatic controller are :

a) Flexible operation

b) High torque high speed operation

c) Fire and explosion proof operation

d) No leakage

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8. Hydraulic controller :

a) Flexible operation

b) High torque high speed operation

c) Fire and explosion proof operation

d) No leakage

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9. Electronic Controller :

a) Flexible operation

b) High torque high speed operation

c) Fire and explosion proof operation

d) No leakage

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10. A plant controlled by a proportional controller. If a time delay element is introduced in the loop its :

a) Phase margin remains the same

b) Phase margin increases

c) Phase margin decreases

d) Gain margin increases

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## Set 3

1. Fluid power circuits use schematic drawings to:

a) Simplify component function details

b) Make it so only trained persons can understand the functions

c) Make the drawing look impressive

d) Make untrained person to understand

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2. A pneumatic symbol is:

a) Different from a hydraulic symbol used for the same function

b) The same as a hydraulic symbol used for the same function

c) Not to be compared to a hydraulic symbol used for the same function

d) None of the mentioned

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3. Pneumatic systems usually do not exceed:

a) 1 hp

b) 1 to 2 hp

c) 2 to 3 hp

d) 4 to 5 hp

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4. Most hydraulic circuits:

a) Operate from a central hydraulic power unit

b) Use air-over-oil power units

c) Have a dedicated power unit

d) Does not have dedicated power unit

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5. Hydraulic and pneumatic circuits:

a) Perform the same way for all functions

b) Perform differently for all functions

c) Perform the same with some exceptions

d) Does not perform all the functions

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6. The lubricator in a pneumatic circuit is the:

a) First element in line

b) Second element in line

c) Last element in line

d) Third element in line

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7. Series circuits work on both hydraulic and pneumatic actuators.

a) True

b) False

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8. When comparing first cost of hydraulic systems to pneumatic systems, generally they are:

a) More expensive to purchase

b) Less expensive to purchase

c) Cost is same

d) Cost is not required

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9. When comparing operating cost of hydraulic systems to pneumatic systems, generally they are.

a) More expensive to operate

b) Less expensive to operate

c) Cost is same to operate

d) Cost is not required

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10. The most common hydraulic fluid is:

a) Mineral oil

b) Synthetic fluid

c) Water

d) Gel

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## Set 4

1. The constant M circle for M=1 is the

a) straight line x=-1/2

b) critical point (-1j0)

c) circle with r= 0.33

d) circle with r=0.67

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2. The polar plot of a transfer function passes through the critical point (-1,0). Gain margin is

a) Zero

b) -1dB

c) 1dB

d) Infinity

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3. Consider the following statements:

1. The effect of feedback is to reduce the system error

2. Feedback increases the gain of the system in one frequency range but decreases in another

3. Feedback can cause a system that is originally stable to become unstable

Which of these statements are correct.

a) 1,2 and 3

b) 1 and 2

c) 2 and 3

d) 1 and 3

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4. The open loop transfer function of a system is G(s) H(s)= K / (1+s)(1+2s)(1+3s)

The phase cross over frequency ωc is

a) V2

b) 1

c) Zero

d) V3

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5. If the gain of the open-loop system is doubled, the gain margin

a) Is not affected

b) Gets doubled

c) Becomes half

d) Becomes one-fourth

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6. The unit circle of the Nyquist plot transforms into 0dB line of the amplitude plot of the Bode diagram at

a) 0 frequency

b) Low frequency

c) High frequency

d) Any frequency

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7. Consider the following statements:

The gain margin and phase margin of an unstable system may respectively be

1. Positive, positive

2. Positive, negative

3. Negative, positive

4. Negative, negative

Of these statements

a) 1 and 4 are correct

b) 1 and 2 are correct

c) 1, 2 and 3 are correct

d) 2,3 and 4 are correct

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8. If a system has an open loop transfer function

1-s / 1+s, then the gain of the system at frequency of 1 rad/s will be

a) 1

b) 1/2

c) Zero

d) -1

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9. The polar plot of the open loop transfer function of a feedback control system intersects the real axis at -2. The gain margin of the system is

a) -5dB

b) 0dB

c) -6dB

d) 40dB

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10. The corner frequencies are

a) 0 and 1

b) 0 and 2

c) 0 and 1

d) 1 and 2

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11. For the transfer function

G(s) H(s) = 1 / s(s+1) (s+0.5), the phase cross-over frequency is

a) 0.5 rad/sec

b) 0.707 rad/sec

c) 1.732 rad/sec

d) 2 rad/sec

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12. The gain margin (in dB) of a system having the loop transfer function

G(s) H(s) = 2 / s(s+1) is

a) 0

b) 3

c) 6

d) 8

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13. The gain margin for the system with open loop transfer function

G(s) H(s) = G(s) =2(1+s) / s2 is

a) 8

b) 0

c) 1

d) -8

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14. Statement 1: In constant M circles, as M increases from 1 to 8 radius of circle increases from 0 to 8 and Centre shifts from (-1,0) to (-8,0)

Statement 2: The circle intersects real axis at point (-1/2, 0)

a) Statement 1 is TRUE, 2 is FALSE

b) Statement 1 is FALSE, 2 is TRUE

c) Statement 1 & 2 TRUE

d) Statement 1 & 2 FALSE

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## Set 5

1. Assertion (A): The zeroes on the real axis near the origin are generally avoided in design.

Reason (R): In a sluggish system introduction of zeroes can improve the transient response

a) Both A and R are true and R is correct explanation of A

b) Both A and R are true but R is not correct explanation of A

c) A is true but R is false

d) A is false but R is true

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2. Addition of zero increases the stability.

a) True

b) False

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3. Zeroes are defined as:

a) Roots of the denominator of the closed loop transfer function

b) Roots of the numerator of the closed loop transfer function

c) Parts of the numerator

d) Parts of the denominator

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4. As zero moves sufficiently left from the origin the effect of zero becomes less pronounced.

a) True

b) False

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5. If number of poles are greater than number of zeroes then the system is known as ______________

a) Stable system

b) Unstable system

c) Minimum phase system

d) Non-minimum phase system

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6. A control system is generally met with the time response specifications:

a) Steady state accuracy

b) Damping factor

c) Setting time

d) All of the mentioned

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7. Steady state accuracy specified in terms of:

a) Steady state error

b) Damping ratio

c) Natural frequency

d) All of the mentioned

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8. Steady state accuracy is determined by suitable choice of____________

a) Steady error

b) Error constants

c) Damping

d) Transient error

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9. Damping factor specifies:

a) Peak overshot to step input.

b) Steady state error

c) Damping ratio

d) Natural frequency

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10. If rise time is also taken into consideration it should be ____________ to the settling time.

a) Inconsistent

b) Consistent

c) Perfect

d) Unique