Difficulty: Easy
Correct Answer: the same as
Explanation:
Introduction / Context:
Wet-bulb temperature (WBT) reflects evaporative cooling potential. At saturation (RH = 100%), air cannot accept more moisture, so evaporation from a wetted wick ceases and WBT converges to dry-bulb temperature (DBT).
Given Data / Assumptions:
Concept / Approach:
At saturation, the partial pressure of water vapour equals the saturation pressure at that temperature. No net evaporation occurs from the wick, eliminating evaporative cooling. Therefore, WBT = DBT at the saturation state.
Step-by-Step Solution:
Verification / Alternative check:
On a psychrometric chart, lines of constant WBT meet the saturation curve exactly at the same point as DBT, confirming equality at RH = 100%.
Why Other Options Are Wrong:
“Lower” or “higher” occur only for unsaturated air; “unrelated” and “always 0°C” are physically incorrect.
Common Pitfalls:
Assuming some evaporation persists at 100% RH; in ideal measurement, none does.
Final Answer:
the same as
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