Question:easy
Low air velocity will be measured by
Low air velocity will be measured by
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Think of a heated-alcohol thermometer whose cooling rate reveals the speed of air movement.
Updated On: Jun 23, 2026
- Kata thermometer
- Globe thermometer
- Wet thermometer
- Beckmans thermometer
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The Correct Option is A
Solution and Explanation
Concept -- instruments in environmental health:
Low air velocity (air current) measurement requires a specialised instrument sensitive to slow-moving air. The Kata thermometer fulfills this role.
Mechanism: The Kata thermometer is a large-bulb alcohol thermometer. Its bulb is warmed in hot water to above 38 degrees C, then held in the air. The time (in seconds) for the alcohol to fall from 38 degrees C to 35 degrees C is recorded. Using the Kata factor engraved on the instrument and a formula, the cooling power and hence the air velocity are calculated.
Why the others are wrong:
- Globe thermometer: measures radiant temperature (used in WBGT index)
- Wet bulb thermometer: measures humidity
- Beckmans thermometer: measures small temperature differences, not air velocity
\[\boxed{\text{Kata thermometer}}\]
Low air velocity (air current) measurement requires a specialised instrument sensitive to slow-moving air. The Kata thermometer fulfills this role.
Mechanism: The Kata thermometer is a large-bulb alcohol thermometer. Its bulb is warmed in hot water to above 38 degrees C, then held in the air. The time (in seconds) for the alcohol to fall from 38 degrees C to 35 degrees C is recorded. Using the Kata factor engraved on the instrument and a formula, the cooling power and hence the air velocity are calculated.
Why the others are wrong:
- Globe thermometer: measures radiant temperature (used in WBGT index)
- Wet bulb thermometer: measures humidity
- Beckmans thermometer: measures small temperature differences, not air velocity
\[\boxed{\text{Kata thermometer}}\]
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