A barometer made of very narrow tuve (see fig) is placed at normal temperature and pressure. The coefficient of volume expansion of mercury is `0.00018per C^@` and that of the tube is negligible. The temperature of mercury in the barometer is now raised by `1^@C`, but the temperature of the atmosphere does not raised by `1^@C`, but the temperature of the atmosphere does not change. Then the mercury height in the tube remains unchanged.

Explanation

`h=(P_(0))/(rhog)`