Q: The number of particles crossing a unit area in a unit time is given by n =-D (n_{2}-n_{1} )/(x_{2} – x_{1} ) where n_{1} and n_{2} are number of particles per unit volume for the value of x meant x_{1} and x_{2} . Find dimensions of D, the diffusion constant

(a) [M^{0} LT^{2} ]

(b) [ML^{2} T^{-4} ]

(c) [M^{0} LT^{-3} ]

(d) [M^{0} L^{2} T^{-1} ]

Ans: (d)