Cuestionario: Fundamentals of Temperature Measurement — 5 preguntas

1. How would you convert 25°C to Kelvin for precise scientific measurement?

A. 298.15 K

B. 275.15 K

C. 298.5 K

D. 298 K

Answer: (A)

Explicación

To convert 25°C to Kelvin, you add 273.15 to the Celsius temperature, resulting in 298.15 K. This direct application of the formula ensures accurate scientific measurement.

2. What is the primary cause of increased molecular vibration in a system?

A. A change in the chemical composition of molecules

B. An increase in temperature of the system

C. A reduction in thermal energy

D. A decrease in temperature of the system

Answer: (B)

Explicación

An increase in temperature of the system causes more vigorous molecular vibration because temperature is directly connected to the vibrational activity of molecules. Higher temperature indicates higher thermal energy, which results in increased molecular vibrations.

3. What physical principle allows shape change measurement with bimetallic strips?

A. The electrical resistance change in metals due to temperature.

B. The change in color of metals with temperature.

C. The different thermal expansion rates of two bonded metals cause bending.

D. The melting point of metals varies with temperature.

Answer: (C)

Explicación

The correct answer is that the different thermal expansion rates of two bonded metals cause bending, which is the fundamental principle behind shape change measurement with bimetallic strips. This differential expansion results in a physical deformation that can be used to measure temperature.

4. What does the voltage output of a thermocouple represent?

A. The change in resistance of the thermocouple material

B. The direct temperature at the hot junction

C. The electrical current flowing through the thermocouple

D. The temperature difference between the hot and cold junctions

Answer: (D)

Explicación

The voltage output of a thermocouple is proportional to the temperature difference between its hot and cold junctions, as it is generated by the Seebeck effect based on this difference, not the absolute temperature at a single point.

5. What is a key property of thermistors, especially NTC types, that makes them useful for temperature sensing?

A. Resistance remains constant regardless of temperature

B. Resistance increases as temperature increases

C. Resistance decreases as temperature increases

D. Resistance fluctuates unpredictably with temperature

Answer: (C)

Explicación

In typical NTC thermistors, resistance decreases as temperature increases. This property allows them to be used effectively for temperature measurement and regulation, as their resistance change is predictable and correlates with temperature.