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Question
A glass contains some water at room temperature 20°C. Refrigerated water is added to it slowly. when the temperature of the glass reaches 10°C, small droplets condense on the outer surface. Calculate the relative humidity in the room. The boiling point of water at a pressure of 17.5 mm of mercury is 20°C and at 8.9 mm of mercury it is 10°C.
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Solution
Here ,
Dew point = `10^circ` C [∵ Dew appears at `10^circ`C]
At boiling point, SVP equals atmospheric pressure.
At `20^circ` C , SVP = 17.5 mmHg
At dew point , SVP = 8.9 mmHg
`"RH" = ("SVP at dew point") /("SVP at air temperature") xx 100%`
= `8.9/17.5 xx 100%`
= 51%
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