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Questions and Answers
Dissimilar metals joined at their ends produce an electromotive force that is independent of the temperature difference between the junctions.
Dissimilar metals joined at their ends produce an electromotive force that is independent of the temperature difference between the junctions.
False
A bimetallic thermometer consists of a bi-metallic element that expands and contracts with temperature changes.
A bimetallic thermometer consists of a bi-metallic element that expands and contracts with temperature changes.
True
Electrical resistance thermometers are commonly used in aviation to measure temperature.
Electrical resistance thermometers are commonly used in aviation to measure temperature.
True
Thermometers classified by substance include types such as gas thermometers and optical pyrometers.
Thermometers classified by substance include types such as gas thermometers and optical pyrometers.
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The helix in a bimetallic thermometer winds or unwinds to cause a pointer to rotate against a scale calibrated in degrees Fahrenheit.
The helix in a bimetallic thermometer winds or unwinds to cause a pointer to rotate against a scale calibrated in degrees Fahrenheit.
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The temperature at which equilibrium exists between ice and vapour saturated air at a pressure of 760 mmHg is known as the ______.
The temperature at which equilibrium exists between ice and vapour saturated air at a pressure of 760 mmHg is known as the ______.
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In the Celsius scale, the steam point is taken as ______ degrees.
In the Celsius scale, the steam point is taken as ______ degrees.
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Absolute zero is defined as ______ degrees Celsius on the Kelvin scale.
Absolute zero is defined as ______ degrees Celsius on the Kelvin scale.
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The Fahrenheit scale divides the fundamental interval into ______ degrees.
The Fahrenheit scale divides the fundamental interval into ______ degrees.
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Substances expand as their temperature rises; thus, a measure of temperature can be obtained by measuring equal amounts of ______.
Substances expand as their temperature rises; thus, a measure of temperature can be obtained by measuring equal amounts of ______.
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Study Notes
Air Temperature Measurement
- Air temperature is measured using instruments.
- Temperature is a measure of hotness or coldness.
- Ice point is the temperature where ice and vapor are in equilibrium at 760 mmHg pressure.
- Steam point is the temperature where liquid water and vapor are in equilibrium at 760 mmHg pressure.
- Fundamental interval is the difference in temperature between two fixed points (e.g., ice point and steam point).
Temperature Scales
- Celsius scale divides the fundamental interval into 100 degrees, with ice point at 0°C and steam point at 100°C.
- Fahrenheit scale divides the interval into 180 degrees, with ice point at 32°F and steam point at 212°F.
- The Kelvin scale starts at absolute zero (-273.15°C or 273.15°C below freezing point).
Methods of Temperature Measurement
- Measurement is based on property changes that vary with temperature (e.g., expansion/contraction of solids, liquids or gases).
- Thermal expansion is a key principle.
- Liquid expansion, vapor pressure change, electrical resistance changes, electromotive force (emf) generation and light emission can all measure temperature.
Types of Thermometers
- Bimetallic Thermometers: Use a bimetallic strip that bends with temperature change to indicate changes on a scale.
- Electrical Resistance Thermometers: (Resistance Thermometers) use the change in the electrical resistance of a material (usually metal) with temperature changes to measure temperature.
- Thermocouples: Utilize the electromotive force produced at the junction of two dissimilar metals to measure temperature differences or changes in temperature. They're commonly used for higher temperatures.
Errors in Air Temperature Gauges
- Instrument errors: Variations in manufacturing.
- Environmental errors: Sun heating the sensor can affect measurement.
- Heating errors: Friction/air compression (significant in high-speed aircraft).
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Description
This quiz explores the fundamentals of air temperature measurement, including key temperature scales such as Celsius, Fahrenheit, and Kelvin. It also discusses the principles behind measuring temperature using various methods, along with the concepts of ice point and steam point. Test your understanding of how temperature is defined and measured!
