Re: ¿cual es el metodo para medir el grosor de una pared de una burbuja jabon

There are several ways.

Here are two of the easiest

(1) You can measure the size of the bubble. And you can measure its weight 
(mass):

         mass (in milligram) = pi * d * d * t

where pi = 3.14159...
      d is the diameter of the bubble in millimetre
      t is the thickness of the film in millimetre

This uses the geometric formula for the volume of a spherical shell, and the 
fact that 1 cubic millimetre of water weighs almost exactly 1 milligram.

It is possible, but difficult to determine the mass directly on a balance; 
an easier way is to measure the downward velocity of the bubble in still 
air. A bubble has a good spherical shape, and settles very slowly, so the 
Stokes equation for terminal velocity works well:

v = m * g / (3 * eta * pi * d) 

where m is the mass of the bubble, g is the gravitational acceleration (a 
constant), and eta is the viscosity of air. Care with and conversion factors 
for units would also be needed.

(2) You can use the colours that you see in the film. These colours are made 
by interference between light rays that reflect off the front wall of the 
bubble, and light rays that reflect off the back wall. If the distance 
between the front wall and back wall is an exact number of wavelengths, 1, 
2, 3, etc. then the two reflected rays will be in step, and that colour will 
appear strongly. If it is a half-wavelength out-of-step, then the two rays 
will tend to cancel, and that colour will be weakest -- 0.5, 1.5, 2.5 
wavelengths, etc. Ordinary white light is a mixture of all wavelengths. In 
air, visible red light has 700 nm wavelength (=0.0007 mm), and visible 
violet light has 400 nm wavelength (=0.0004 mm), and the other colours come 
in between. In water, these wavelengths shorten by a factor of 1.33 (the 
refractive index) to 0.000525 mm and 0.000300 mm respectively. So if you 
measure the spectrum of white light reflected from a soap bubble, and note 
the position of the peaks and troughs, you can work out the difference in 
path length between the reflected ray that does not enter the bubble, and 
the one that goes twice through the thickness of it, in reflecting off the 
back wall.