Copernicus. |
Helio-Centric Model. |
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Copernicus. |
Helio-Centric Model. |
Tyrannosaurus rex (T. rex) went extinct around 65 million years ago. |
“All the explanations proposed seem to be only partly satisfactory. They range from massive climatic change to mammalian predation to the extinction of a plant with apparent laxative properties, in which case the dinosaurs died of constipation.”---CARL SAGAN.
Particle Nature of light: Einstein's Explanation.
He also proposed that a quantum of light has linear momentum and the magnitude of that linear momentum is p=h/c. The individual light quantum of definite energy and momentum can be associated with a particle. can behave as a particle and this is called photon. Therefore, photon is nothing but particle manifestation of light.
Light is made up of particles called Photons. |
Characteristics of photons:
According to particle nature of light, photons are the basic constituents of any radiation and possess the following characteristic properties:
i) The photons of light of frequency v and wavelength & will have energy, given by E=hv= hc/λ
ii) The energy of a photon is determined by the frequency of the radiation and not by its intensity and the intensity has no relation with the energy of the individual photons in the beam.
iii) The photons travel with the speed of light and its momentum is given by hhv P=h/λ =hv/c
iv) Since photons are electrically neutral, they are unaffected by electric and magnetic fields.
v) When a photon interacts with matter (photon-electron collision), the total energy, total linear momentum and angular momentum are conserved. Since photon may be absorbed or a new photon may be produced in such interactions, the number of photons may not be conserved.
“Matter is Energy… Energy is Light…We are all Light Beings” —Albert Einstein.
L'histoire est un ensemble de mensonges convenus.
Cinema is the most widely acclaimed means of entertainment in the world today. It is a combination of various equipments, techniques and art which constitutes cinema. But the most important things needed to experience cinema are camera, film reel and a projector. "Wheel of life' or 'zoopraxiscope' was the first machine to show animated pictures. It was patented in 1867 by William Lincoln. In a zoopraxiscope, moving photographs were watched through a slit.
Zoopraxiscope |
"The cinema is an invention without a future." - Louis Lumière. The Lumiere brothers-Auguste and Louise - are credited for inventing the first motion picture camera in the year, 1895. But even prior to Lumiere brothers, many others had made similar inventions. Lumiere brothers invented a portable motion-picture camera, film processing unit and a projector called the Cinematographe. Here, three functions were covered in one invention.
Lumiere Brothers |
Cinematographe |
Cinematographe or Cinematography brought a revolutionary change in the world of cinema and made motion pictures popular. Though, prior in 1891, the Edison Company came up with a kinetoscope which allowed to watch cinema one person at a time, Edison's vitascope (1896) was the first commercially successful projector in USA.
Kinetoscope |
A camera shoots an activity on a film roll, also known as a film negative. This film negative is then edited. An editor removes away unnecessary scenes by cutting away that portion of the film role. Then the edited film roll is processed in a lab with required effects. The final film footage is then mounted on a projector. A projector is a device which projects the film running on the film roll on a blank white screen with the help of light. There are two pulleys on a projector. The film reel is mounted on the first projector and is run through the first to the second projector with the help of a motor.
Advertising of Edson's Vitascope |
The film reel passes between a magnifying lens and a light bulb. The lens increases the size of the image on the blank white screen.
Cinematography is an art form unique to motion pictures. Although the exposing of images on light-sensitive elements dates back to the early 19th century, motion pictures demanded a new form of photography and new aesthetic techniques. In the infancy of motion pictures, the cinematographer was usually also the director and the person physically handling the camera. As the art form and technology evolved, a separation between the director and the camera operator emerged. With the advent of artificial lighting and faster (more light sensitive) film stocks, in addition to technological advancements in optics and new techniques such as colour film and widescreen, the technical aspects of cinematography necessitated a specialist in that area.
"IF A MILLION PEOPLE SEE MY MOVIE, I HOPE THEY SEE A MILLION DIFFERENT MOVIES." ---QUENTIN TARANTINO---
Dir. QUENTIN TARANTINO.
X-rays, like the light are electromagnetic radiations and are not visible to the eye. Their wavelengths are smaller than those of the visible light. They are high energy rays. That is why they have high penetrating power. They can pass through the flesh of our body. They travel with the velocity of light.
X-Rays image of the human hand. |
These rays were discovered by Prof. Wilhelm Conrad Roentgen in 1895. They are sometimes called 'Roentgen rays' also. They were called X-rays (X-means unknown) because these were not known earlier. For this wonderful discovery Prof. Roentgen was awarded the first Nobel Prize of Physics in 1901 .
Wavelength of the Electro-magnetic waves. |
The apparatus used for producing X-rays is called 'X-rays tube'. This tube is made up of hard glass and is fitted with two electrodes which are connected to high voltage D.C. source. The electrode connected to the negative terminal is called cathode and the one connected to positive terminal is called anode. Low pressure is created inside the tube by pumping out air from it. When high voltage is applied between the electrodes, electrons emerge from the cathode and hit the 'anode' or the 'target'. As a result the X-rays come out of the tube.
X-rays are very useful for us. They can pass through substances like wood, paper, skin, flesh etc. but are absorbed by bones, iron,lead etc. Doctors make use of X-rays to detect the dislocations and fractures of bones. They are also used to examine the diseases of lungs and presence of stones in kidneys and gall bladder. X-rays are allowed to fall on the body part to be examined and a photograph is taken on the photo film kept behind that part. In this film the portion of bones appears grey. From these X-ray photographs, the disease and defects are located easily.
X-rays are also used in treating cancer. With the help of these rays, gold and other valuable gems hidden in the body are detected easily. They are also used to detect cracks and bubbles in the iron bars used for constructing bridges and buildings. They are used to study the structure of crystals. With these rays, it is very easy to distinguish between natural and synthetic diamonds.
We all know that the sunlight consists of all those colours which are seen in a rainbow. These colours are: violet, indigo, blue, green, yellow, orange and red. Light from the sun travels in the form of waves which are known as electromagnetic waves. The different colours of light have different wavelengths. Our eyes are sensitive only to the wavelengths relating to the above seven colours. Apart from the wavelengths of these seven colours, the sunlight consists of radiations of other wavelengths also, but our eyes are not sensitive to them. Rays having wavelengths higher than that of red light are called infra-red rays and those lower than violet light are called ultraviolet rays. Both infra-red and ultraviolet rays are not visible to our eyes.
Spectral Lines. |
Infra-red rays come not only from the sun but from every hot object. Burning wood and coal, electric heater-all produce these rays. These can be recorded on special type of photographic films made of infra-red sensitive materials. Whenever these rays fall on any material body they produce heat. They are very useful to us.
Wavelength of Infrared Radiation. |
Infra-red radiations are being used for the treatment of several diseases. Special types of infra-red lamps are used for treating the pains of muscles and joints-especially for backpain. They are also used for heating rooms in winter.
Animals Pictures taken under IR Camera. |
Infra-red radiations are being used for the guidance and control of missiles and other ballistic weapons. These radiations are also used for transmitting and receiving invisible signals. Molecular structures are studied with the help of these radiations. Impurities present in the materials can also be detected by these rays.
Light, The Visible Reminder of Invisible Light ---John Green---
Milk and curd looks white when we seen in the sunlight but they appears red in red light and blue in blue light. Have you ever wondered? Why its happens? If you don't know follow my blog page for more curious science thoughts.
We all know that the sunlight is a mixture of seven colours. There are: Violet, Indigo, Blue, Green, Yellow, Orange & Red. The colours of the sun light can be separated with the help of a prism. The coloured an object depends upon the colour that reaches our eyes after reflection from the object.
Colour of an objects depends upon the reflected light. |
What ever colour is reflected by the object, is the colour of the that object. The molecular structure of milk and curd is such that they do not absorb any of the colours of the sunlight but reflected all of them, Thus these substances appear white. When milk and curd are viewed in red light, they look red because red colour is reflected by them. The same argument holds good for the colours of the other objects also.
Colors! What A Deep And Mysterious Language, The Language Of Dreams. -Paul Gauguin.
"Nuclear Power Is One Hell Of A Way To Boil Water" - Albert Einstein.
This conception is in itself not very satisfactory. It is still less satisfactory because it leads to the result that the light emitted by the stars and also individual stars of the stellar system are perpetually passing out into infinite space, never to return, and without ever again coming into interaction with other objects of nature. Such a finite material universe would be destined to become gradually but systematically impoverished.
The Four Fundamental Forces in Physics.
There are four fundamental forces in physics:
They are Gravitational, Electromagnetic, Strong Nuclear and Weak Nuclear forces.
The Four Fundamental Forces in Physics. |
Gravitational Force:
Gravitational force is a force between two masses and it is universal in nature. Our planets are bound to the sun through gravitational force of the sun. We are in the earth because of Earth's gravitational attraction on our body.
Electromagnetic Force:
Electromagnetic force is a force between two charges, and We are standing on the earth's surface because of the Electromagnetic force between atoms of the surface of the earth with atoms in our feet.
Strong Nuclear Force:
The force between two nucleons, there exists a strong nuclear force and this force is responsible for stability of nucleus. Strong Nuclear force holds the protons and neutrons together in the nucleus of an atom. The atoms in our body are stable is due to strong nuclear force.
Weak Nuclear Force:
Weak force is even shorter in the range than the strong nuclear force. During the fusion of hydrogen into helium in the sun, neutrinos and enormous radiations are produced through weak force.
" A Physicist is just an atom's way of looking itself. "
--Niels Bohr--
Rutherford's Alpha Particles Scattered with Scattering Angle.
In 1911, Geiger and Marsden did the experiment based on the Rutherford's scattering alpha particles by gold foil.
A source of Alpha particles are kept inside a thick lead box with with a hole. The alpha particles coming through the hole made of lead box pass through another hole made on the lead screen. These particles are now allowed to fall on a thin gold foil and it is observed that the alpha particles passing through gold foil are scattered through different angles. A movable screen (from 0° to 180°) which is made up of zinc sulphide (ZnS) is kept on the other side of the gold foil to collect the scattered alpha particles. Whenever alpha particles strike the screen, a flash of light is observed which can be seen through a microscope.
Rutherford's Alpha Particles Scattered with Scattering Angle |
Rutherford proposed an atom model based on the results of the alpha scattering experiment. In this experiment alpha particles were allowed to fall on the atoms of a metallic gold foil.
(a) Most of the alpha particles were un-deflected through the gold foil and went straight.
(b) Some of the alpha particles were deflected through a small angle.
(c) A few alpha particles (one in thousand) were deflected through the angle more than 90°.
(d) Very few alpha particles returned back (back scattered) - that is, deflected back by 180°.
" An alleged scientific discovery has no merit unless it can be explained to a barmaid. "
---Ernest Rutherford---
The Davisson-Germer Experiment is a key experiment that confirms the wave nature of particles, specifically electrons, as predicted by de ...