The tube of mercury barometer is 4mm in diameter. How much error does the surface tension cause in the reading? Surface tension of mercury = `540" x "10^(-3) Nm^(-1)`, angle of contact = `135^(@)`. Density of mercury `= 13.6 xx 10^(3)kg m^(-3)`.

Answer

`Depression 0.2293 xx 10^(-2)m`

Explanation

Error in the reading of barometer=depression of mercury level caused due to surface tension`=(2S cos theta)/(r rho g) = (2xx540xx10^(-3)xxcos 135^@)/((5//2)xx10^(-3) xx(13.6xx10^3)xx9.8)`
= - 0.002293m