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# Brownian Motion

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 Sub Topics The Brownian movement was first described in 1828 by the botanist Robert Brown, while investigating the pollen of several plants. For more than half a century following, a score of scientists studied this motion, common to organic and inorganic particles of microscopic size when suspended in a liquid, to determine the causes and dynamics of the motion.

## What is Brownian Motion?

Brownian motion is described as a random motion present in the case of gas or liquid (fluid), which results in the collision of the molecule present in the substance. In other words, we can say that Brownian motion is a zig zag motion of molecules.

Standard Brownian motion: It is a continuous time stochastic process. Another name of this motion is Wiener process.

## Brownian Motion Equation

Mathematical expression of Brownian motion is mentioned below:
D = $\frac{RT}{N_{A}6\pi \eta a}$

D = $\frac{k_{B}T}{6\pi \eta a}$
where,
R
is the gas constant,
T is the temperature,
$\eta$ is the viscosity,
a is the radius of the brownian particle

## What causes Brownian Motion?

The main causes of Brownian motion is listed below:
• The dispersed molecules are collide with dispersion medium continuously
• Due to this collision, molecules moves randomly
• Since it is a random motion, it is not in a straight line motion

So, this motion is the result of unequal bombardment of dispersed molecules and medium.