Question

Why must the thermometers in a sling psychrometer be swung in order to obtain the readings?

A) To prevent evaporation
B) To increase accuracy
C) To decrease accuracy
D) No effect on readings

Answer 1

Swinging a sling psychrometer ensures air movement over the bulbs for accurate evaporation from the wet-bulb, leading to precise humidity readings. The correct answer is to increase accuracy.

Step-by-step explanation:

The thermometers in a sling psychrometer must be swung to obtain accurate readings because the action of swinging the device helps ensure that air is moving over the bulbs consistently. This is especially important for the wet-bulb thermometer, as the movement of air over the wet wick facilitates the evaporation of water, which in turn affects the temperature reading.

The process of evaporation is endothermic, meaning it absorbs heat, which cools down the wet-bulb thermometer. This evaporation would not occur as efficiently if the air were still, which would lead to inaccurate readings of humidity when the wet-bulb and dry-bulb temperatures are compared. Therefore, the correct answer to the question is B) To increase accuracy.