KNOW PHYSICS

Dark Matter in a nutshell  Introduction  The matter in which the modern scientists are higly interested in is the Dark Matter. So, what is Dark Matter? How it was formed? Who suggested the idea of Dark matter? How much amount of it is in the universe? Does it interact with other particles? What is Baryonic Matter? Can we detect dark matter or has anyone detected it till now? Let find out. Also subscribe the blog for email notifications. What is Dark Matter? Dark matter is a type of matter. Dark matter is called Dark because it does not appear to interact with electromagnetic field, which means it doesn't absorbs, reflect or emit electromagnetic radiations, and is therefore difficult to detect. Primary Evidences The primary evidence comes from the calculations done after studying about different galaxies in the universe.It was observed that may of the galaxies would fly apart, not move as they move or even do not form until and unless they contain a large

BROWNIAN MOTION Introduction One of the most asked question is- what is Brownian Motion? Brownian motion was first observed in 1827 by Brown, a botanist. The phenomenon of Brownian movement can be easily observed in a laboratory if a colloidal solution is examined under and ultramicroscope. As the direction of illumination is perpendicular to the axis of the microscope, the suspended particles in the solution look like bright illuminated spots.  Is eliminated particles continuously move to and fro in a random haphazard way. The particles spin, rise, sink and rise again. The movement of the particles is continuous and spontaneous. This non-stop random and haphazard motion is perpetual and spontaneous.                  Click here for-  Our FACEBOOK PAGE So, what is Brownian Motion? This non-stop, random and haphazard motion is called Brownian Motion. According to Albert Einstein's theory of transitional Brownian Motion, the particles tend to diffuse into the

Quantum Mechanics #3 Black Body A perfectly black body is one which absorbs totally all the radiation of any wavelength which fall on it. As it neither reflects nor transmits any radiation, it appears black; whatever be the colour of incident radiation. The main characteristic of such a body is that when heated to a suitable high temperature, it emits full or total radiation. As it is a perfect absorber, it is also a perfect radiator, its emission being the greatest possible for every wavelength at any given temperature. BLACK BODY Black Body in Practice  In practice, a perfectly black body is not available. Lamp-black and Platinum black are the nearest approach to a black body. However, a body showing close approximation to a perfectly black body can be constructed. Black Body absorber                   Black body emitter A closed chamber, say a hollow sphere (known as hollow spherical cavity) whose inner surface is coated with platinum black or lamp

INTRODUCTION  The failure of classical mechanics led Planck(in 1900) to the discovery that radiation is emitted in quanta whose energy is E=hν. In 1901, Planck was able to derive an empirical formula to explain the experimentally observed distribution of energy in the spectrum of a black body, on the basis of his revolutionary hypothesis known as quantum theory of heat radiation. This was the  Origin of quantum Mechanics(click here) Max Karl Ernst Ludwig Planck According to this theory, the energy distribution is given by This realtion agrees (and hence completely fit) with the experimental curves obtained. This formula of distribution of energy with wavelengths, on the basis of his quantum concept, was deduced using following assumptions, which may be called as Planck's quantum postulates. PLANCK'S QUANTUM POSTULATES  1) A black body contains the atomic oscillators capable of vibrating with all possible frequencies. An oscillator of frequency ν can not have a

INTRODUCTION What is Quantum mechanics?| Quantum Mechanics is the theory which attempts to explain the behaviour  of matter and interaction with energy on the scale of atoms and atomic particles i.e., particles of the size of the order of   1/10¹⁰ metres. Phenomena such as motion of mechanical objects involving distances larger than about  1/10⁶ metres can be explained satisfactorily by laws of classical theoretical physics which is based on the following basic laws :  1) Newton's Laws of motion,  2) Newton's inverse square law of gravitational attraction between two bodies,  3) Coulomb's inverse square law of attraction or repulsion between two electrically charged bodies,  4) The law of force on a moving charge in a magnetic field, i.e., the Lorentz force. However, certain phenomena such as spectral distribution of energy in blackbody radiation, Photoelectric effect etc; and phenomena involving distances of the order of 1/10¹⁰ metres could not b

X-Rays  Introduction X rays discovered by William Roentgen in 1895 honoured by Nobel Prize in 1901. Basically are high energy photons (1- 100Kev) or electro-magnetic radiation, having a very short wavelength of the order of 1A⁰. Typical x-ray wavelength lies between the range of  1 A⁰ and 100A⁰. Accordingly they are classified into hard X-rays and soft X-rays.  Uses of X rays are multifold. Usually they are used in surgery, radiotherapy, engineering, industry, detective department, scientific research and so many other areas. Hence, the name X-rays is popularly known even to a common man. Production Of X-RAYS The modern X-ray tube was designed by Dr.Coolidge and is known after his name as coolidge tube. It is widely used for commercial and medical purposes. Construction and working of Coolidge Tube The construction of coolidge tube to produce X-rays is schematically shown below. The cathode C consists of a tungsten filament  heated by passing a current th

STATISTICAL MECHANICS: A BRIEF HISTORY Statistical mechanics was initiated in 1870 with the work of Austrian physicist Ludwig Boltzmann, much of which was collectively published in Boltzmann's 1896 lectures on gas theory. Statistical mechanics provided a molecular level interpretation of microscopic thermodynamic quantities such as eork, heat, free energy and entropy. The study of statistical physics is mainly classified into categories. These are: Classical statistics or Maxwell-Boltzmann statistics. Quantum statistics or Bose -Einstein and Fermi-Dirac statistics. STATISTICAL BASIS Statistics is that branch of science which deals with the collection, classification and tabulation of numerical data as the basis of explanation, description and comparison of various phenomenon. When statistical concepts are applied to physics, the new branch that emerges is called statistical physics. Statistical physics deals with macroscopic systems. i.e. the system consisting