Question 1

What is the z-transform of the signal x[n] = an u(n)?

Accepted Answer

A)  x(z)  =1/z-1
B)  x(z)  = 1/1-z
C)  x(z)  = z/z-a
D)  x(z)  = 1/z-a C

Question 2

A controller is basically a ---

Accepted Answer

A)  sensor
B)  comparator
C)  amplifier
D)  clipper B

Question 3

Zero initial condition for a system means

Accepted Answer

A)  input reference signal is zero
B)  zero stored energy
C)  no initial movement of moving parts
D)  system is at rest and no energy is stored in any of its components D

Question 4

Z and Laplace transform are related by:

Accepted Answer

A)  s = ln z
B)  s =ln z/t
C)  s =z
D)  s= t/ln z

Question 5

Which one of the following rules determine the mapping of s-plane to z-plane?

Accepted Answer

A)  right side of the s-plane maps into outside of the unit circle in z-plane
B)  left half of s-plane maps into inside of the unit circle
C)  imaginary axis in s-plane maps into the circumference of the unit circle
D)  all of the mentioned

Question 6

Analysis of control system by Laplace transform technique is not possible for

Accepted Answer

A)  discrete time systems
B)  linear systems
C)  time invarient systems
D)  unstable continuous time systems

Question 7

A zero order hold is used with sampled data system to

Accepted Answer

A)  make it critically damped
B)  reconstruct the sampled signal
C)  improve the stability of the system
D)  convert it to a continuous system

Question 8

If the z transform of x(n) is X(z) =z(8z-7)/4z2 -7z+3, then the final value theorem is :

Accepted Answer

A)  1
B)  2
C)   ?
D)  0

Question 9

Sampling is necessary :

Accepted Answer

A)  in complex control systems
B)  where high accuracy is required
C)  non automated control systems
D)  automated control system

Question 10

The first step required to convert analog signal to digital is :

Accepted Answer

A)  sampling
B)  holding
C)  reconstruction
D)  quantization

Question 11

The first order control system ,which is well designed has a

Accepted Answer

A)  small bandwidth
B)  negative time constant
C)  large negative transfer function pole
D)  none of the above

Question 12

Z-transform is used in:

Accepted Answer

A)  continuous optimal control problem
B)  discrete optimal problem
C)  control systems
D)  none of the mentione

Question 13

Zero-order hold used in practical reconstruction of continuous-time signals is mathematically represented as a weighted-sum of rectangular pulses shifted by:

Accepted Answer

A)  any multiples of the sampling interval
B)  integer multiples of the sampling interval
C)  one sampling interval
D)  1 second intervals

Question 14

Which of the following is an advantage of Laplace transform method

Accepted Answer

A)  it gives solution in frequency domain only
B)  it gives total solution more systematically
C)  initial conditions are incorporated in the very first step
D)  both b & c

Question 15

Sampling can be done by:

Accepted Answer

A)  impulse train sampling
B)  natural sampling
C)  flat-top sampling
D)  all of the mentioned

Question 16

Unit step response of the system described by the equation y(n) +y(n-1) =x(n) is:

Accepted Answer

A)  z2/(z+1) (z-1) 
B)  z/(z+1) (z-1) 
C)  z+1/z-1
D)  z(z-1) /z+1

Question 17

Difference equation model results in:

Accepted Answer

A)  sampled-data systems
B)  numerical analysis of continuous time systems
C)  continuous time feedback systems
D)  both a & b

Question 18

A control system working under unknown random actions is called ---

Accepted Answer

A)  computer control system
B)  digital data system
C)  stochastic control system
D)  adaptive control system

Question 19

The signal is reconstructed back with the help of

Accepted Answer

A)  zero order hold circuits
B)  extrapolations
C)  signal is reconstructed with zero order holds and extrapolations
D)  signal is not reconstructed

Question 20

_______________ is a sampling pattern which is repeated periodically

Accepted Answer

A)  single order sampling
B)  multi order sampling
C)  zero order sampling
D)  unordered sampling

Exam 1: Control Systems, Sampling, and Transform Techniques

What is the z-transform of the signal x[n] = an u(n) ?