Derive an expression for the excess of pressure inside a liquid drop

1.	Derive an expression for the excess of pressure inside a liquid drop
Answer» Consider a liquid drop of radius R and surface tension T.\xa0Due to surface tension the molecules on the surface film experience the net force in inward direction normal to the surface.Therefore there is more pressure inside than outside.Let pi\xa0be the pressure inside the liquid drop and po\xa0be the pressure outside the drop.\xa0Therefore excess of pressure inside the liquid drop is, p = p1– p0Due to excess of pressure inside the liquid drop the free surface of the drop will experience the net force in outward direction due to which the drop will expand.Let the free surface displace by dR under isothermal conditions.\xa0Therefore excess of pressure does the work in displacing the surface and that work will be stored in the form of potential energy.The work done by excess of pressure in displacing the surface is,\xa0dW = Force x displacement = (Excess of pressure x surface area) x displacement of surfaceIncrease in the potential energy is,dU = surface tension x increase in area of the free surfaceThe above expression gives us the pressure inside a liquid drop.\xa0

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