1.

In the previous question, suppose contact angle is not zero, but it is theta (the surface not hemispherical) now find pressure at point 'A'.

Answer»

Solution :
DRAW normal (radial lines) at point `A` and `B` of periophery. The point `(C)` WHERER radial lines meet is called centre of curvture. If contact angle is `theta`, from `Delta ACM, r_(C) = R sectheta`
So RADIUS of curvature of the surface `r_(C) = R sectheta`
Point to remember :
If the LIQUID surface is hemispherical `(theta = 0)` then `r_(c) = R`
If liquid surface is not hemispherical `(theta ne 0)` then `r_(c) = R sec theta`

So pressure at `A` is `P_(0) - (2T)/(Rsectheta) + rhogh`


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