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Question 1

Three most common non-contact sensors

Answer 1

1) Inductor Proximity Sensor
2) Capacitance Proximity Sensor
3) Optical

Question 2

Inductor Proximity Sensor

Answer 2

Only detects the presence of electrically conductive material
-Detects electrically conductive materials (mostly metals)
-None contact sensor
-Working Principle: A proximity sensor which detect eddy currents which caused magnetic loss

Question 3

Capacitance Proximity Sensor

Answer 3

This is a noncontact sensor which can detect non conductive materials by inducing a negative current on the material is trying to detect
-The ability to detect depends on the materials ability to electrically charge
-Can detect nonmetallic objects
-Working Principle: Detects the changes in capacitance between the sensor and the object(this is affected by the distance between objects and size of the object)

Question 4

Eddy Currents

Answer 4

Are loops of current within conductors which results due to a changing Magnetic Field

Question 5

Optical Proximity Sensor

Answer 5

-Light generated at frequency is best detected by an optical sensor
-Working Principle: The sensor emits a light and hits the object it is detected the sensor is then able to sense the light reflected off of that object to measure proximity

Question 6

Hall Effect Sensor

Answer 6

Is an electrical instrument which able to sense the hall effect to provide a measurement of varying Magnetic Field

Question 7

LVDT

Answer 7

-linear variable Differential Transformer

Question 8

Electromagnetic linear velocity transducer

Answer 8

-Made of a stationary coil and a permanent magnetic core within the coil
-The object which the velocity is being measured is attached to the core and as the core moves velocity is being measured
-Works do to the principle of electromotor force and Magnetic fields

Question 9

Vibration

Answer 9

-Oscillatory Motion about an equilibrium point
-The motion is due to an initial force

Question 10

Natural Vibration

Answer 10

VIbration caused by a one time force (applied and then removed

Question 11

Forced Vibration

Answer 11

Vibration caused by a constant force

Question 12

Variable Capacitive Sensor

Answer 12

A change in capacitance that due to temperature, humidity or other physical parameters can be converted to a voltage to help measure change in position
-can measure force and acceleration

Question 13

What is a Piezoelectric Vibration Sensor

Answer 13

-An instrument that measures vibration
-When a force applied to a plate a stress is induced in the crystal along with a corresponding deformation this leads to a potential difference which it used to measure vibration

Question 14

Sound Measurements

Answer 14

-Vibratory Phenomenon
-Acoustic effects are usually measured in terms of harmonic pressure fluctuations produced in a liquid or gaseous medium

Question 15

The Quantization Error is numerically equal to the magnitude of the LSB (True or False)

Answer 15

True

Question 16

A reverberant room is usually used to measure directivity factor or index of sound source. (True or False)

Answer 16

False

Question 17

Phon

Answer 17

1000 Hz (1 KHz)

Question 18

Explain the difference between the Student t distribution and the Chi-square distribution

Answer 18

-They both test for differences between two groups
-Chi square is used when you have two categorical variables

Question 19

The magnitude of the output voltage of a piezoelectric material is;

Answer 19

Directly proportional to its change sensitivity

Question 20

Low-frequency motion is likely to exhibit high-amplitude for the accelerations even though displacement amplitude may be large.

Answer 20

False

Question 21

Name two Advantage of using Piezoelectric Acelometer for vibration measurement

Answer 21

1) high frequency
2) dynamic measurements

Question 22

A vibration sensor (accelerometer) having a natural frequency of 20 kHz, is best used to measure structural vibrations with frequency range.

Answer 22

10 Hz to 5000Hz

Question 23

Discuss the operating principle of a capacitive vibration sensor.

Answer 23

A change in capacitance is caused by a physical variable such temp, humidity, etc. which allows the sensor to measure vibration

Question 24

When μ = 1 and σ = 2 the probabiity density function pd(x) is called the standard normal distribution. (True or False)

Answer 24

False

Question 25

As the degrees of freedom ν approach infinity, the t distribution approaches
A. the Gama distribution
B. the Chi-square distribution
C. the standard normal distribution.
D. the random distribution

Answer 25

Standard Normal Distribuition

Question 26

Due to their fragility, piezoelectric vibration sensors are usually used to measure lower range of vibration frequency compared to LVDT sensors.
True or False

Answer 26

False

Question 27

Explain why the quantization error magnitude is equal to the LSB

Question 28

Determining flow rate measurements using a venture flowmeter are based on

Answer 28

Pressure Differential

Question 29

In a vibration sensor, the natural undamped frequency of the seismic mass is lower than its damped natural frequency. (True and False)

Answer 29

False

Question 30

The magnitude of the output voltage of a capacitive level sensor

Answer 30

Is proportional to dielectric constant vibrations variations with liquid level

Question 31

The Nyquist frequency is.

Answer 31

highest frequency of interest to be captures using a sampling rate

Question 32

The zero-order uncertainty is related to the hysteresis error in the sensor. (True or False)

Answer 32

FALSE

Question 33

The RSS method can be used to

Answer 33

determine the cumulative uncertainty in a measurement