Deck 17: Temperature Sensing Devices

Question 1

Metal expands when heated. The amount of expansion is proportional to what two factors?

Answer 1

The amount of expansion is proportional to the type of metal used and the amount of temperature.

Question 2

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

Answer 2

True

Question 3

When a metal bar is mechanically held at one end, it permits the amount of expansion to be in one direction.

Answer 3

True

Question 4

Why must electrical contacts never be permitted to open or close too slowly?

Question 5

When two dissimilar metals are joined at one end, and that junction is heated, a voltage is produced. This is known as the ____________________.

Question 6

Describe a bimetal strip.

Question 7

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

Question 8

The ____________________ is the most common heat sensing device used in the production of room thermostats and thermometers.

Question 9

Name the two different types of thermistors.

Question 10

The amount of voltage produced by a thermocouple is determined by what two things?

Question 11

Thermocouples produce high voltages.

Question 12

A very common device that uses the principle of expanding metal to operate a set of contacts is the ____________________ relay found in the refrigeration industry.

Question 13

The resistance temperature detector (RTD) is made of ____________________ wire.

Question 14

A common method of sensing a change of temperature is by the increase of pressure of some chemicals.

Question 15

Figure 17-11

The accompanying figure is showing a(n) ____________________.