Question

A barometer with a brass scale correct at `0^(@)C` reads `70 cm` of mercury on a day when the air temperature is `40^(@)C`. The correct reading at `0^(@)C` is (Coefficient of real exapansion of mercury is `0.00018//^(@)C` and coefficient of linear expansion of brass is `0.00018//^(@)C)`
A. `60.5cm`
B. `69.97cm`
C. `20.5cm`
D. `50.00cm`

Answer 1

Correct Answer - B
`H_(0)rho_(0)g = H_(1)rho_(1)g,H_(0)rho_(0) = H(1 + alphat)(rho_(0))/((1 + gammat))`
`:. H_(0) = H[1 - (gamma - alpha)t]`