Lag1989 problem number 8.39

To calculate the Avogadro number NA, Perrin determined by means of a microscope the height distribution of the spherical gummigut particles suspended in water. He found that the ratio of the number of particles in the layers separated by each other at a distance of L = 38 μm is 2.08. The density of the gummigus is 1.2 * 10³kg / m³, the radii of its particles are R = 0.212 µm. Water temperature is 18 ° C. Using this data, find the Avogadro number.