Which law states that the amount of a substance crossing a given area is directly proportional to the area available for diffusion, concentration gradient and diffusion coefficient?

Fick Law of Diffusion: Diffusion is well described by Fick law of diffusion. According to this law, amount of a substance crossing a given area is directly proportional to the area available for diffusion, concentration gradient and a constant known as diffusion coefficient. Thus,  Amount diffused = Area x Concentration gradient x Diffusion coefficient Formula of Fick law: