(a) The brass scale of a barometer gives correct reading at `0^(@)C` . Coefficient of linear expansion of brass is `2.0xx10^(-5)//^(@)C` . The barometer reads `75cm` at `27^(@)C` . What is the atmospheric pressure at `27^(@)C` ? (b) A barometer reads `75.0cm` on a steel scale. The room temperature is `30^(@)C` . The scale is correctly graduated for `0^(@)C ` . The coefficient of linear expansion of steel is `alpha=1.2xx10^(-5)//^(@)C` and the coefficient of volume expansion of mercury is `gamma=1.8xx10^(-4)//^(@)C` . Find the correct atmospheric pressure.

(a) The brass scale of a barometer gives correct reading at `0^(@)C` .

1.	(a) The brass scale of a barometer gives correct reading at `0^(@)C` . Coefficient of linear expansion of brass is `2.0xx10^(-5)//^(@)C` . The barometer reads `75cm` at `27^(@)C` . What is the atmospheric pressure at `27^(@)C` ? (b) A barometer reads `75.0cm` on a steel scale. The room temperature is `30^(@)C` . The scale is correctly graduated for `0^(@)C ` . The coefficient of linear expansion of steel is `alpha=1.2xx10^(-5)//^(@)C` and the coefficient of volume expansion of mercury is `gamma=1.8xx10^(-4)//^(@)C` . Find the correct atmospheric pressure.
Answer» Correct Answer - `75.0405 cm` `h = h_(0) (1+alpha Delta theta)` `h = 75 {1+ 0.00002 xx 27}` `h = 75.0405 cm`