ANODE RAYS AND DISCOVERY OF PROTONS

ANODE RAYS AND DISCOVERY OF PROTONS



The existence of positively charged particle in an atom was shown by GOLDSTEIN in 1886. He repeated the discharge tube experiments by using a perforated cathode. On applying a high voltage at low pressure, Goldstein observed a new type of rays emerging from the holes in the cathode. These rays traveled in a  direction opposite to that of the cathode rays. These rays were called ANODE RAYS, CANAL RAYS or POSITIVE RAYS.

The charge to mass ratio (e/m) of the particles in the anode rays was found to depend upon the nature of the gas in the discharge tube. The e/m value was found to be maximum when hydrogen gas was taken in the discharge tube. This means that the positive particles formed hydrogen are the lightest. These lightest positively charges particles were named  PROTONS.

The charge on this particle has been found to be equal in magnitude but opposite in sign of that of electron, 

DISCOVERY OF THE ELECTRON - CATHODE RAYS AND PROPERTIES OF CATHODE RAYS

DISCOVERY OF THE ELECTRON - CATHODE RAYS



The electron was discovered as a result of the study of conduction of electricity through gases at low pressures. The experiments were conducted in discharge tubes. When a high potential is applied to a gas taken in a discharge tube at very low pressure, certain rays are emitted from the cathode. These rays are called CATHODE RAYS


PROPERTIES OF CATHODE RAYS


From the various experiments carried out by J.J Thomson  and others, the cathode rays have been found to possess the following properties.

1. They start from cathode and move towards the anode in straight lines.
2. Cathode rays consist of material particles.
3. When an electric field is applied to a stream of cathode rays, they get deflected  towards the positive plate of the electric field. This shows that the particles in the cathode rays carry negative charge.
4. Cathode rays are deflected by magnetic fields in a direction expected for negative particles.
5. Cathode rays produce X-rays when they strike against the surface of hard metals like tungsten, copper etc.
6. Materials coated with fluorescent or phosphorescent substances produce glow when hit by cathode rays.

                       All these observations led to the conclusion that cathode rays consist of fast moving negatively charged particles. These particles were named ELECTRONS.

CALLIGRAPHY

 C a L L i G r A P h Y

      CALLIGRAPHY IS BEAUTIFULLY FORMED LETTERING. The term applies to written text and illumination ( the decoration of manuscripts using gold leaf and colour). The essential materials needed to practice  calligraphy are a writing tool, ink and a writing surface. Quills are among the oldest writing tools. They are usually made from goose or turkey feathers and are noted for their flexibility and ability to produce fine lines. A quill point, how ever is not very durable and constant re cutting and trimming   is required. The most  commonly used writing instrument in western calligraphy is a detachable, metal nib held in a pen holder. The metal nib is very durable, and there are wide range of different types. Particular types of nibs- such as copper plate, speed ball and round hand nibs-are used for specific styles of lettering. Some nib has internal ink reservoirs and others have reservoirs that are detachable. Brushes are also used for writing  and for filling in outlined letters and painting decoration. Other writing tools used in calligraphy are fountain pens, felt-tip pens, rot ring pens and reed pens. Calligraphy inks may come in liquid form, or as a solid ink stick. Ink sticks are ground down in distilled water to form a liquid ink. The most common writing surface for calligraph are good quality, smooth surfaced papers. To achieve the best writing position, the calligrapher places the paper on a drawing board set at an angle.    

           

ASTEROIDS, COMETS, AND METEOROIDS

ASTEROIDS, COMETS, AND METEOROIDS 

ASTEROIDS, COMETS, AND METEOROIDS  are all debris remaining from the nebula in which the solar system formed 4.6 billion years ago. Asteroids are rocky bodies up to about 1,000 km in diameter, although most are smaller. Most  of them orbit the sun in the asteroid belt, which lies between the orbits of mars and Jupiter. Comets may originate in a huge cloud (called the Oort cloud) that is thought to surround the solar system. They are made of frozen gases and dust, and are a few km in diameter. Occasionally, a comet is deflected from the Oort cloud to the orbit the sun in a long, elliptical path. As the comet approaches the sun, the comet's surface starts to vaporize  in the heat, producing  a  brightly shining coma (a huge sphere of gas and dust around the nucleus ), a gas tail, and a dust tail. Meteoroids are small chunks of stone or stone and iron, some of which  are fragments of asteroids  or comets. Meteoroids range in size from tiny dust particles to objects tens of meters across. If a meteoroid enters the Earth's atmosphere, it is heated by friction and appears as glowing streak of light called a meteor ( also known as a shooting star). Meteor showers occur when the Earth passes through the trail  of dust particles left by a comet. Most meteors burn up in the atmosphere. The few that are large enough to reach the Earth's surface are termed meteorites.  

CHEMICAL REACTIONS

CHEMICAL REACTIONS



A CHEMICAL REACTION TAKES PLACE whenever bonds between atoms are broken or made. In each case atoms or groups of atoms are rearranged, making new substances (products) from the original ones (reactants). Reactions happen naturally, or can be made to happen; they may take years or only a instant. Some of the main types are shown here. A reactions   usually involves a change in energy. In a burning reaction, for example, the  making of new bonds between atom releases energy heat and light. This type of reaction, in which heat is given off, is an exothermic reaction. Many reactions, like burning are irreversible, but in some cases the reactions are reversible (reaction in either directions). Reactions can be used to form solids from solutions; in a double decomposition reaction two compounds in solution break down and re-form into two new substance,often creating a precipitate (insoluble solid); in displacement an element (eg.copper) displace another element (eg. silver) from a solution. The rate  (speed) of a reaction is determined by the shape of the reactants. To describe and keep track of reactions, internationally recognized chemical symbols and equations are used. Reactions are also used in laboratory to identify matter. An experiment with candle wax, for example demonstrates that it contains carbon and hydrogen.

KOOKABURRA BIRD (habit)

KoOkAbURrA BirD

The Kookaburra's rolling, laughing call is one of the best known-sounds in the animal World. The birds raise a wild chorus of crazy laughter as they go to roost in the tree tops at dusk, and again wake everyone with in hearing just as dawn breaks, so regularly that in the hinter lands of Australia they are known as the "bushman's clock". Australians value the Kookaburra, not only as an intriguing member of the strange fauna, but for its habit of feeding on snakes and lizards. The Kookaburra seizes snakes behind the head and kills them by dropping them from a height, or else carries them to a perch and batters them senseless with its big bill before swallowing them. Less welcome is the Kookaburra's fondness for the young of other birds, and its occasional raids on farmyards for ducklings and baby chicks. In the wild, Kookaburra  are known to be partial to be young of other birds and snakes, as well as insects and small reptiles. In the zoo they are fed commercially prepared bird of prey mix and dead baby chicks. Kookaburras generally live in pairs or in small groups in open woodland. The incubate their two or four pure white eggs in hollow tree trunks, tree holes or in excavated termite nests. Both adults incubate for a period of 25 days. The young leave the next 30 days after hatching, but the parents continue to fees them for another 40 days.

AIR

A i R

The air we breathe has seventeen different gases. It is made up mostly of nitrogen, not Oxygen. Recently, human activities have changed the balance in the Earth's atmosphere. Atmosphere is the air that surrounds the  Earth. The wide spread burning of coal and oil increases the levels of carbon monoxide gas. Scientists believe this air pollution may cause Global warming. Certain chemicals used in the air conditioners, farming and manufacturing are the problem. They break down the ozone layer around the Earth. With less protection from the sun the air temperature rises and makes the Earth warmer. This leads to harmful effects on people, farming, animals and the natural environment.