Two vertical parallel glass plates are partically submerged in water. The distance between the plates is `d=0.10mm`, and their width is `l=12cm` assuming that the water between the plates does not reach the upper edges of the plates and the wetting is complete, it is found that the force of their mutual attraction, is `(n+20)N`. What is the value of n? `(T=0.073(N)/(m))`

Answer

4

Explanation

Then `P_(0)-P_(A)=` excess pressure `=(T)/((d)/(2))=(2T)/(d)`
`P=` average pressure of water between plates.
`=(P_(A)+P_(B))/(2),F=F=((2T)/(d)-(1)/(2)rhog.(2T)/(drhog))xx(2Tl)/(drhog)`
Hence, `n=3`.