Question

a drop of olive oil of radius 0.30 millimetres into a nearly circular film of radius 12 CM on the water surface estimate the molecular size of olive oil

Answer 1

Solution:-

gievn by , 
Radius of the drop = 0.30mm
= 0.30 x 10^-3 m 

Volume of the oil drop = (4/3)×(pi)×(0.30x 10^-3)^3 ..............(1) 

The circular film is cylinderical with radius 0.12m (given) and thickness 't' m(say). 

Volume of the film = (pi) × (0.12)^2 × t .......(2) 

at equat to equetion》

(4/3)×(pi)×(0.30x 10^-3)^3 =(pi) × (0.12)^2 × t

t = ((4/3)×(pi)×(0.30x 10^-3)^3)/(pi) × (0.12)^2

t =( 4/3)×(0.30x 10^-3)^3/144×10^4

t = (36×10^-6)/144×10^4

t = 0.25×10^-10


NOTE: We have found only the thickness of the film and not the size of the oil molecule.