Evidence for existence of particles, Physics

Assignment Help:

The idea that everything is made up of very small particles has been developed over many years supported by several experiments:

(i)               Brownian motion: Robert Brown was an English botanist who, in the year 1827, observed pollen grains floating on water under a microscope. He observed that pollen grains moved arbitrarily over the surface of water.

This arbitrary motion of pollen grains was named Brownian motion and later explained to be caused because of collision of the water molecules with the pollen grains. The water molecules are too small to be seen with any microscope, but it is evident from movement of pollen grains that the water molecules exist and are in constant random motion.

(ii)              

Dilution of colour: if we add a drop of ink to the beaker full of water it will be observed that the ink spreads throughout the water until all the water is coloured. This is because the ink particles take up the spaces inbetween the water molecules and, as they are in constant random motion, the ink particles spreads evenly throughout the water. 

(iii)               Diffusion of gases: gases mix with each other by diffusion (process by which the solute moves from the region of high concentration to the region of low concentration). The common examples include the spread of a fragrance from 1 end of a room to another or from 1 room to another.

                Diffusion of bromine from 1 gas jar to the other

Experimentally diffusion can be checked by the reaction of hydrogen chloride gas with ammonia. 2 cotton balls, 1 soaked in hydrochloric acid and another in the ammonia solution, are placed at opposite ends of a glass tube and ends are sealed.

After some time the white fumes of ammonium chloride forms where the 2 gases mix. The fume is seen nearer the hydrochloric acid, as hydrochloric acid, as it is heavier, diffuses slower than ammonia.

 


Related Discussions:- Evidence for existence of particles

What are the main types of laser, What are the main types of laser? Typ...

What are the main types of laser? Types of lasers are as illustrated below: a. Solid State lasers b. Raman laser c. Semiconductor lasers d. Dye lasers e. Gaseous

Diode, #shockly diode equation..

#shockly diode equation..

Calculate the capacitance of the capacitor, A parallel plate capacitor has ...

A parallel plate capacitor has nineteen interleaved plates each 75mm by 75mm separated by mica sheets 0.2mm thick. Assuming the relative permittivity of the mica is 5. Calcu

Balmer series, Balmer series (J. Balmer; 1885) An equation that describ...

Balmer series (J. Balmer; 1885) An equation that describes the emission spectrum of hydrogen while an electron is jumping to the second orbital; four of the lines are into the

Define term practical optical fibre in short, Define term practical optical...

Define term practical optical fibre in short. Optical fibre: A practical optical fibre has in common three coaxial areas. The innermost area is the light guiding region term

Classical free electron theory, Classical free electron theory: The ...

Classical free electron theory: The free  electron theory of metals using classical laws was developed by Dude and Lorentz in the beginning of last century. That time the va

Daltons law of partial pressures, Dalton's law of partial pressures (J. Dal...

Dalton's law of partial pressures (J. Dalton) The overall pressure of a mixture of ideal gases is equivalent to the total of the partial pressures of its components; i.e., the

Determine joules of heat if energy dissipated by resistor, The potential di...

The potential difference across a 4 ohm resistor is 20 volts.  Assuming that all of the energy dissipated by this resistor is in the form of heat, how many joules of heat are radia

Scalar and vector, example of problems of vector and scalar with solution

example of problems of vector and scalar with solution

Expression for the frequencies of coupled oscillatory system, Two similar s...

Two similar simple pendulums each of length ‘l' and mass ‘m' are coupled by a spring of force constant ‘k'. Write down the expression for the normal mode frequencies of the coupled

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd