11. Instead, single particle identification and correlation are implemented, which set limits on particle number density . 12. Astrophysicists prefer to use number density to describe these environments, in units of particles per cubic centimetre. 13. Well the number density of dry air is about 2.5 * 10 25 m-3. 14. Count ( or number ) per liter is used to measure number density in a variety of domains. 15. Where is the atomic number density , the absorption cross section, the length of the wave vector and 16. The reaction rate ( fusions per volume per time ) is times the product of the reactant number densities : 17. The net force on a surface particle, pulling it into the container, is proportional to the number density 18. Multiply the volume by the photon number density to get the total number of photons in the observable universe. 19. The assumption here is that either the extinction coefficient \ alpha or the column number density N is known. 20. The basic distribution function uses the Boltzmann constant k and temperature T with the number density to modify the normal distribution:
