Final Test

Question 1

In the mercury bulb switch, how is the differential level of the liquid determined?

Answer 1

Having bulb switch at different height in the tank.

Question 2

Float switches are used to control the action of a(n) ____________________ in accordance with the level of a liquid in a tank or sump.

Answer 2

Pump

Question 3

In the bubbler system, the pressure required to bubble air through the pipe is directly proportional to the ____________________ of the liquid in the tank

Answer 3

Height

Question 4

The ____________________ gauge is ideal for measuring the level of turbulent, aerated, solids-laden, viscous, corrosive fluids.

Answer 4

Microwave level

Question 5

Float switches can be used to pump water from a tank or sump. T or F?

Answer 5

False

Question 6

A great advantage of the bubbler system is that the pressure switches are located outside the tank, which makes it unnecessary to open the tank to service the system. T or F?

Answer 6

True

Question 7

The bubbler system operates on the principle that as the liquid level increases in the tank, it requires less air pressure to blow air through the line in the tank. T or F?

Answer 7

False

Question 8

A great advantage of the microwave level gauge is that no mechanical object touches or is inserted into the product. T or F?

Answer 8

True

Question 9

In a mercury bulb switch, when the liquid level is below the position of the bulb, it is suspended in a horizontal position. T or F?

Answer 9

False

Question 10

The bubbler system employs the use of float switches. T or F?

Answer 10

True

Question 11

The microwave level gauge operates by emitting a high frequency signal of approximately 24 GHz. into a tank and then measuring the frequency difference of the return signal that bounces off the product. T or F?

Answer 11

True

Question 12

In the bubbler system, a pressure switch is used to adjust the maximum air flow. T or F?

Answer 12

False

Question 13

The operation of a float switch is controlled by the upward or downward movement of a float in a tank of liquid. T or F?

Answer 13

True

Question 14

What type of float switch does not have a differential setting?

Answer 14

Mercury Bulb float switch

Question 15

Flow switches are used to detect the ____________________ of air or liquid through a duct or pipe

Answer 15

Pressure

Question 16

Low air flow switches are often called ____________________.

Answer 16

Sail

Question 17

The air flow switch is constructed from a snap action micro switch. T or F?

Answer 17

True

Question 18

Regardless of the type of flow switch used, a single pole double throw micro switch is generally contained. T or F?

Answer 18

True

Question 19

Flow switches are used to control high current loads. T or F?

Answer 19

False

Question 20

Regardless of whether a flow switch is intended to detect the movement of air or liquid, the NEMA symbol for both is the same. T or F?

Answer 20

True

Question 21

Air flow switches are often used in air conditioning and refrigeration circuits to give a positive indication that the evaporator or condenser fan is operating before the compressor is permitted to start. T or F?

Answer 21

True

Question 22

There are two basic types of thermistors: one type has a negative temperature coefficient (NTC) and the other has a positive temperature coefficient (PTC). T or F?

Answer 22

True

Question 23

A thermistor that has a positive temperature coefficient will decrease its resistance as the temperature increases. T or F?

Answer 23

False

Question 24

Because of their nonlinear characteristics, thermistors are often used as set point detectors as opposed to actual temperature measurement. T or F?

Answer 24

True

Question 25

When two dissimilar metals are joined at one end, and that junction is heated, a voltage is produced. This is known as the Faraday’s heating. T or F?

Answer 25

False

Question 26

The resistance temperature detector (RTD) is made of silver wire. T or F?

Answer 26

False

Question 27

The amount of voltage produced by the Hall generator is determined by the amount of current flowing through the semiconductor material and the strength of the magnetic field used to deflect the current path. T or F?

Answer 27

True

Question 28

Hall effect limit switches uses a hall generator instead of a set of contacts. T or F?

Answer 28

False

Question 29

Position sensors have the ability to sense the intensity of the magnetic field. T or F?

Answer 29

False

Question 30

Hall effect linear transducers can be obtained that have regulated output or ratiometric output. T or F?

Answer 30

True

Question 31

Photoconductive devices exhibit change of resistance due to presence or absence of an object. T or F?

Answer 31

False

Question 32

One advantage to photo-emissive devices is speed. T or F?

Answer 32

True

Question 33

Photo-detectors have to make physical contact to detect an object. T or F?

Answer 33

False

Question 34

Ultrasonic Proximity Detectors operate by emitting a pulse of low-frequency sound. T or F?

Answer 34

False

Question 35

When an object is brought into proximity to a capacitive proximity detector a change of capacitance cause detector to activate. T or F?

Answer 35

True

Question 36

When Photovoltaic (silicon) devices are used they will produce 5 volts in the presence of direct sunlight. T or F?

Answer 36

False

Question 37

Photovoltaic detector is able to produce ___________ in presence of light

Answer 37

Voltage

Question 38

Proximity detectors gives ability to sense red hot metals. T or F?

Answer 38

True