# Multiple choice question for engineering

## Set 1

1. Which of the following transfer function will have the greatest maximum overshoot?

a) 9/(s^{2}+2s+9)

b) 16/(s^{2}+2s+16)

c) 25/(s^{2}+2s+25)

d) 36/(s^{2}+2s+36)

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2. A system generated by The ramp component in the forced response will be:

a) t u(t)

b) 2t u(t)

c) 3t u(t)

d) 4t u(t)

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^{2}Taking the inverse Laplace transform the forced term is 2t u(t).

3. The system in originally critically damped if the gain is doubled the system will be :

a) Remains same

b) Overdamped

c) Under damped

d) Undamped

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4. Let c(t) be the unit step response of a system with transfer function K(s+a)/(s+K). If c(0+) = 2 and c(∞) = 10, then the values of a and K are respectively.

a) 2 and 10

b) -2 and 10

c) 10 and 2

d) 2 and -10

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5. The damping ratio and peak overshoot are measures of:

a) Relative stability

b) Speed of response

c) Steady state error

d) Absolute stability

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6. Find the type and order of the system given below:

a) 2,3

b) 2,2

c) 3,3

d) None of the mentioned

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7. A system has a complex conjugate root pair of multiplicity two or more in its characteristic equation. The impulse response of the system will be:

a) A sinusoidal oscillation which decays exponentially; the system is therefore stable

b) A sinusoidal oscillation with a time multiplier ; the system is therefore unstable

c) A sinusoidal oscillation which rises exponentially ; the system is therefore unstable

d) A dc term harmonic oscillation the system therefore becomes limiting stable

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8. The forward path transfer function is given by G(s) = 2/s(s+3). Obtain an expression for unit step response of the system.

a) 1+2e^{-t}+e^{-2t}

b) 1+e^{-t}-2e^{-2t}

c) 1-e^{-t}+2e^{-2t}

d) 1-2e^{-t}+e^{+2t}

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^{2}+3s+2) C(s) = 1/s-2/s+1+1/s+2 c(t) = 1-2e

^{-t}+e

^{+2t}.

9. Find the initial and final values of the following function:

F(s) = 12(s+1)/s(s+2)^2(s+3)

a) 1,∞

b) 0,∞

c) ∞,1

d) 0,1

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10. The step response of the system is c(t) = 10+8e^{-t}-4/8e^{-2t} . The gain in time constant form of transfer function will be:

a) -7

b) 7

c) 7.5

d) -7.5

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## Set 2

1. Which of the following transfer function will have the greatest maximum overshoot?

a) 9/(s^{2}+2s+9)

b) 16/(s^{2}+2s+16)

c) 25/(s^{2}+2s+25)

d) 36/(s^{2}+2s+36)

### View Answer

2. A system generated by The ramp component in the forced response will be:

a) t u(t)

b) 2t u(t)

c) 3t u(t)

d) 4t u(t)

### View Answer

^{2}Taking the inverse Laplace transform the forced term is 2t u(t).

3. The system in originally critically damped if the gain is doubled the system will be :

a) Remains same

b) Overdamped

c) Under damped

d) Undamped

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4. Let c(t) be the unit step response of a system with transfer function K(s+a)/(s+K). If c(0+) = 2 and c(∞) = 10, then the values of a and K are respectively.

a) 2 and 10

b) -2 and 10

c) 10 and 2

d) 2 and -10

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5. The damping ratio and peak overshoot are measures of:

a) Relative stability

b) Speed of response

c) Steady state error

d) Absolute stability

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6. Find the type and order of the system given below:

a) 2,3

b) 2,2

c) 3,3

d) None of the mentioned

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7. A system has a complex conjugate root pair of multiplicity two or more in its characteristic equation. The impulse response of the system will be:

a) A sinusoidal oscillation which decays exponentially; the system is therefore stable

b) A sinusoidal oscillation with a time multiplier ; the system is therefore unstable

c) A sinusoidal oscillation which rises exponentially ; the system is therefore unstable

d) A dc term harmonic oscillation the system therefore becomes limiting stable

### View Answer

8. The forward path transfer function is given by G(s) = 2/s(s+3). Obtain an expression for unit step response of the system.

a) 1+2e^{-t}+e^{-2t}

b) 1+e^{-t}-2e^{-2t}

c) 1-e^{-t}+2e^{-2t}

d) 1-2e^{-t}+e^{+2t}

### View Answer

^{2}+3s+2) C(s) = 1/s-2/s+1+1/s+2 c(t) = 1-2e

^{-t}+e

^{+2t}.

9. Find the initial and final values of the following function:

F(s) = 12(s+1)/s(s+2)^2(s+3)

a) 1,∞

b) 0,∞

c) ∞,1

d) 0,1

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10. The step response of the system is c(t) = 10+8e^{-t}-4/8e^{-2t} . The gain in time constant form of transfer function will be:

a) -7

b) 7

c) 7.5

d) -7.5

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## Set 3

1. Which of the following is not the feature of modern control system?

a) Quick response

b) Accuracy

c) Correct power level

d) No oscillation

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2. The output of the feedback control system must be a function of:

a) Reference input

b) Reference output

c) Output and feedback signal

d) Input and feedback signal

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3. The principle of homogeneity and superposition are applied to:

a) Linear time invariant systems

b) Nonlinear time invariant systems

c) Linear time variant systems

d) Nonlinear time invariant systems

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4. In continuous data systems:

a) Data may be continuous function of time at all points in the system

b) Data is necessarily a continuous function of time at all points in the system

c) Data is continuous at the inputs and output parts of the system but not necessarily during intermediate processing of the data

d) Only the reference signal is continuous function of time

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5. A linear system at rest is subject to an input signal r(t)=1-e^{-t}. The response of the system for t>0 is given by c(t)=1-e^{-2t}. The transfer function of the system is:

a) (s+2)/(s+1)

b) (s+1)/(s+2)

c) 2(s+1)/(s+2)

d) (s+1)/2(s+2)

### View Answer

^{-2t}R(s)=1/s-1/s+1 C(s)=1/s-1/s+2 Tf=2(s+1)/(s+2).

6. In regenerating the feedback, the transfer function is given by

a) C(s)/R(s)=G(s)/1+G(s)H(s)

b) C(s)/R(s)=G(s)H(s)/1-G(s)H(s)

c) C(s)/R(s)=G(s)/1+G(s)H(s)

d) C(s)/R(s)=G(s)/1-G(s)H(s)

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7. A control system whose step response is -0.5(1+e^{-2t}) is cascaded to another control block whose impulse response is e^{-t}. What is the transfer function of the cascaded combination?

a) 1/(s+2)(s+1)

b) 1/(s+1)s

c) 1/(s+3)

d) 0.5/(s+1)(s+2)

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8. A transfer function has two zeroes at infinity. Then the relation between the numerator(N) and the denominator degree(M) of the transfer function is:

a) N=M+2

b) N=M-2

c) N=M+1

d) N=M-1

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9. When deriving the transfer function of a linear element

a) Both initial conditions and loading are taken into account

b) Initial conditions are taken into account but the element is assumed to be not loaded

c) Initial conditions are assumed to be zero but loading is taken into account

d) Initial conditions are assumed to be zero and the element is assumed to be not loaded

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10. If the initial conditions for a system are inherently zero, what does it physically mean?

a) The system is at rest but stores energy

b) The system is working but does not store energy

c) The system is at rest or no energy is stored in any of its part

d) The system is working with zero reference input

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## Set 4

1. The input of a controller is

a) Sensed signal

b) Error signal

c) Desired variable value

d) Signal of fixed amplitude not dependent on desired variable value

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2. Phase lag controller:

a) Improvement in transient response

b) Reduction in steady state error

c) Reduction is settling time

d) Increase in damping constant

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3. Addition of zero at origin:

a) Improvement in transient response

b) Reduction in steady state error

c) Reduction is settling time

d) Increase in damping constant

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4. Derivative output compensation:

a) Improvement in transient response

b) Reduction in steady state error

c) Reduction is settling time

d) Increase in damping constant

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5. Derivative error compensation:

a) Improvement in transient response

b) Reduction in steady state error

c) Reduction is settling time

d) Increase in damping constant

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6. Lag compensation leads to:

a) Increases bandwidth

b) Attenuation

c) Increases damping factor

d) Second order

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7. Lead compensation leads to:

a) Increases bandwidth

b) Attenuation

c) Increases damping factor

d) Second order

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8. Lag-lead compensation is a:

a) Increases bandwidth

b) Attenuation

c) Increases damping factor

d) Second order

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9. Rate compensation :

a) Increases bandwidth

b) Attenuation

c) Increases damping factor

d) Second order

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10. Negative exponential term in the equation of the transfer function causes the transportation lag.

a) True

b) False

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## Set 5

1. The auto-correlation function of a rectangular pulse of duration T is

a) A rectangular pulse of duration T

b) A rectangular pulse of duration 2T

c) A triangular pulse of duration T

d) A triangular pulse of duration 2T

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2. The FT of a rectangular pulse existing between t = − T 2/ to t = T / 2 is a

a) Sinc squared function

b) Sinc function

c) Sine squared function

d) Sine function

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3. The system characterized by the equation y(t) = ax(t) + b is

a) Linear for any value of b

b) Linear if b > 0

c) Linear if b < 0

d) Non-linear

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4. The continuous time system described by 2 y(t) = x (t^{2}) is

a) Causal, linear and time varying

b) Causal, non-linear and time varying

c) Non causal, non-linear and time-invariant

d) Non causal, linear and time-invariant

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5. If G( f) represents the Fourier Transform of a signal g (t) which is real and odd symmetric in time, then G (f) is

a) Complex

b) Imaginary

c) Real

d) Real and non-negative

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6. If a periodic function f(t) of period T satisfies f(t) = −f (t + T/2) , then in its Fourier series expansion

a) The constant term will be zero

b) There will be no cosine terms

c) There will be no sine terms

d) There will be no even harmonics

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7. Given a unit step function u (t), its time-derivative is:

a) A unit impulse

b) Another step function

c) A unit ramp function

d) A sine function

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8. The order of a linear constant-coefficient differential equation representing a system refers to the number of

a) Active devices

b) Elements including sources

c) Passive devices

d) None of the mentioned

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9. Z-transform converts convolution of time-signals to

a) Addition

b) Subtraction

c) Multiplication

d) Division

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10. Region of convergence of a causal LTI system

a) Is the entire s-plane

b) Is the right-half of s-plane

c) Is the left-half of s-plane

d) Does not exist