# 2.1 Brownian motion  (Page 3/5)

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The subsequent observations of Theodor Svedberg and Felix Ehrenhaft on Brownian motion in colloids and onparticles of silver in air, respectively, helped to support Einstein’s theory, but much of the experimental work to actuallytest Einstein’s predictions was carried out by French physicist Jean Perrin, who eventually won the Nobel Prize in physics in 1926.Perrin’s published results of his empirical verification of Einstein’s model of Brownian motion are widely credited for finallysettling the century-long dispute about John Dalton’s theory for the existence of atoms.

## Brownian motion and kinetic theory

The kinetic theory of matter states that all matter is made up of atoms and molecules, that these atoms andmolecules are in constant motion, and that collisions between these atoms and molecules are completely elastic.

The kinetic-molecular theory of heat involves the idea that heat as an entity is manifested simply in the form ofthese moving atoms and molecules. This theory is comprised of the following five postulates.

• Heat is a form of energy.
• Molecules carry two types of energy: potential and kinetic.
• Potential energy results from the electric force between molecules.
• Kinetic energy results from the motion of molecules.
• Energy converts continuously between potential energy and kinetic energy.

Einstein used the postulates of both theories to develop a model in order to provide an explanation of theproperties of Brownian motion.

Brownian motion is characterized by the constant and erratic movement of minute particles in a liquid or agas. The molecules that make up the fluid in which the particles are suspended, as a result of the inherently random nature of theirmotions, collide with the larger suspended particles at random, making them move, in turn, also randomly. Because of kinetics,molecules of water, given any length of time, would move at random so that a small particle such as Brown’s pollen would be subject toa random number of collisions of random strength and from random directions.

Described by Einstein as the “white noise” of random molecular movements due to heat, Brownian motion arises fromthe agitation of individual molecules by thermal energy. The collective impact of these molecules against the suspended particleyields enough momentum to create movement of the particle in spite of its sometimes exponentially larger size.

According to kinetic theory, the temperature at which there is no movement of individual atoms or molecules isabsolute zero (-273 K). As long as a body retains the ability to transfer further heat to another body – that is, at any temperatureabove absolute zero – Brownian motion is not only possible but also inevitable.

## Brownian motion as a mathematical model

The Brownian motion curve is considered to be the simplest of all random motion curves. In Brownian motion, aparticle at time t and position p will make a random displacement r from its previous point with regard to time and position. Theresulting distribution of r is expected to be Gaussian (normal with a mean of zero and a standard deviation of one) and to beindependent in both its x and y coordinates.

#### Questions & Answers

what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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biomolecules are e building blocks of every organics and inorganic materials.
Joe
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research.net
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sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
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nano basically means 10^(-9). nanometer is a unit to measure length.
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Anassong
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s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
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Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
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Mostly, they use nano carbon for electronics and for materials to be strengthened.
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is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
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s.
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SUYASH Reply
for screen printed electrodes ?
SUYASH
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s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
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Source:  OpenStax, Nanotechnology: content and context. OpenStax CNX. May 09, 2007 Download for free at http://cnx.org/content/col10418/1.1
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