Friday, June 26, 2009

What is Electricity

Electricity is the flow of electrical power or charge. It is a secondary energy source which means that we get it from the conversion of other sources of energy, like coal, natural gas, oil, nuclear power and other natural sources, which are called primary sources. The energy sources we use to make electricity can be renewable or non-renewable, but electricity itself is neither renewable or non-renewable.

Electricity is a power too, which is a form of energy. It is the flow of electrons. All matter is made up of atoms, and an atom has a center, called a nucleus. The nucleus contains positively charged particles called protons and uncharged particles called neutrons. The nucleus of an atom is surrounded by negatively charged particles called electrons. The negative charge of an electron is equal to the positive charge of a proton, and the number of electrons in an atom is usually equal to the number of protons. When the balancing force between protons and electrons is upset by an outside force, an atom may gain or lose an electron. When electrons are "lost" from an atom, the free movement of these electrons constitutes an electric current.

Power is a basic part of nature and it is one of our most widely used forms of energy. We get power, which is a secondary energy source, from the conversion of other sources of energy, like coal, natural gas, oil, nuclear power and other natural sources, which are called primary sources. Many cities and towns were built alongside waterfalls (a primary source of mechanical energy) that turned water wheels to perform work. Before power generation began slightly over 100 years ago, houses were lit with kerosene lamps, food was cooled in iceboxes, and rooms were warmed by wood-burning or coal-burning stoves. Beginning with Benjamin Franklin's experiment with a kite one stormy night in Philadelphia, the principles of power gradually became understood. In the mid-1800s, Thomas Edison changed everyone's life -- he perfected his invention -- the electric light bulb. Prior to 1879, power had been used in arc lights for outdoor lighting. Edison's invention used power to bring indoor lighting to our homes.

Wednesday, June 24, 2009

How The Moon Shine?

The moon, one of a satellite in the space, rotates on its axis around the earth, and "shines" when the sun's light beams onto its surface, and is reflected back to earth.
The moon shines by reflecting sunlight. Like Earth, half of the moon is always lit by the sun's direct rays, and the other half is in shadow. Unfortunately, only one side of the moon is visible to us on the earth, as it takes the moon the same length of time to orbit on its axis, as it takes for it to orbit the earth.
You may have seen that the moon does not always look round. Remember when the moon travels around Earth, different parts of its bright side are seen from Earth. Without the sun, there would be no moonlight.
The lunar month is divided into halves. During the first half, lasting approximately 14 days, the sun's light unrelentingly strikes the moon, which has no atmosphere or air to protect it from these rays, and brings the temperature of the moon to above that of the boiling point. The second half of the lunar month plunges the moon into cold, dark nights.
A Full Moon rising can be a dramatic celestial sight, and Full Moons can have many names, such as tonight's Full Moon, and Harvest Moon.

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How the Sun shines on the Earth at Different Seasons

Spring Position of the Earth. -- About the 21st of March of each year the earth is in the position A, figure 16, where the line from the sun to the earth is at right angles to the earth’s axis. The sun then illuminates the whole hemisphere of the earth which is turned toward it, from pole to pole. The days and nights are equal all over the earth. This time is called that of the Vernal Equinox, because the season in our hemisphere is spring, and the days and nights are equal.
Summer Position of the Earth. -- Three months later, about June 21, the earth will be in the position B, with the north end of its axis now tipped toward the sun. The sun then shines on the region round the north pole, while that round the south pole is in darkness, as we see by figure 17, which represents the earth in the position B, but on a larger scale.
The circle AC round the north pole of the earth, which touches the edge of the illuminated hemisphere at this time, is called the Arctic Circle. Its radius will be 23½° of the earth's meridian, the same as the obliquity of the ecliptic. As the earth revolves on its axis in this position, the region within the arctic circle will never be carried outside of where the sun is shining. Hence, to an observer in this region the sun will not set on the 21st of June, but will seem to go round the sky in the direction from south through west, north, and east.
Next, imagine a circle, MN, drawn round the south pole of the earth, so as to touch the edge of the illuminated hemisphere. This is called the Antarctic Circle. We see that, as the earth revolves, the region within this circle will not be brought into sunshine at all. Hence the sun will never rise within this circle on June 21.
At a distance of 23½° north of the equator EQ, there is a circle FG on which the sun will be in the zenith at noon of June 21. This circle is called the Tropic of Cancer.
At the equator EQ the days will be equal to the nights. The further north we go from the equator, the larger the fraction of a circle of latitude round the earth which will be sunshine. Hence on the 21st of June the days are longer and the nights shorter as we go toward the north.
South of the equator the days get shorter and the nights longer, as we travel south, until we reach the antarctic circle, when the sun will simply show himself on the horizon at noon.
Autumn Position of the Earth. -- At C, the plane of the equator again passes through the sun, and the latter shines over one hemisphere of the earth, from the north to the south pole. At is time the days and nights are again equal the world over. This is called the Autumnal Equinox, because the days and nights are again equal and the season is autumn.
Winter Position of the Earth. -- On December 21 the earth is in the position D, with the north end of the axis tipped away from the sun, and the south end tipped toward it. Now day and night are the reverse of what they were with the earth at B. Figure 17 will still answer for us, only it is now night where it is represented as day in the figure, and vice versa. All the region within the arctic circle is in darkness, and all that within the antarctic circle in the sunshine. North of the equator the nights are longer than the days; south of it the days are longer than the nights.
The sun passes through the zenith of every place in latitude 23½° south at noon of this day. This circle of latitude is called the Tropic of Capricorn.

How the earthquake happen?

Earthquakes are the shaking of the earth’s surface caused by the earth’s rocky outer layer. Earthquakes occur because of the energy stored within the earth. It is usually due to the strain within the rocks that is suddenly released.

It can happen when two plates rub together. The plates travel in different directions and at different speeds. If one plate is slowly forced underneath the other, pressure builds up until the plates rip a part. This is the process causes the ground to move and called an earthquake.

The damage an earthquake causes depends on where it is and the time it is happening. The size will vary from small to large. Earthquakes can deform the ground, make buildings and other structures collapse, and creates tsunamis (which means large sea waves.) Every year there are several million small earthquakes.

Monday, June 22, 2009

Virus of Computer, what kind of Virus???

Computer viruses have come a long way since their first appearance in the 1970's. As pieces of programming code, they're written to perform a specific function. Viruses can spread through email attachments, application programs on your computer, or application programs installed from disk drives.
This species can copy itself and infect a computer without the permission or knowledge of the owner.
The effects a virus can have on your computer depends on how its been programmed to spread. Programming can be one of two types: resident and nonresident. Nonresident viruses are made up of two processes -one finds files on your computer to infect, and the other duplicates the virus within the files that have been found.

Resident viruses are made up of one process. It's sole function is to duplicate itself throughout your computer system. To do this, resident viruses are programmed to load into the computer's memory. By doing this, the virus itself is activated every time you turn your computer on. This process allows the virus to remain active and spread to other targeted applications on your system for as long as the computer is on.

The term "computer virus" is sometimes used as a catch-all phrase to include all types of malware. Malware includes computer viruses, worms, trojan horses, most rootkits, spyware, dishonest adware, crimeware, and other malicious and unwanted software), including true viruses. Viruses are sometimes confused with computer worms and Trojan Horse, which are technically different. A worm can exploit security vulnerabilities to spread itself to other computers without needing to be transferred as part of a host, and a Trojan horse is a program that appears harmless but has a hidden agenda. Worms and Trojans, like viruses, may cause harm to either a computer system's hosted data, functional performance, or networking throughput, when they are executed. Some viruses and other malware have symptoms noticeable to the computer user, but many are surreptitious.

How to prevent our PC from virus?
Nowadays, computer systems are built to protect themselves against viral infection. The floppy disk drives are quickly becoming a thing of the past, so this point of entry has become less popular. Macro viruses rely on security holes within programs like Microsoft Office, so the newer versions of these programs are less vulnerable, but can still be infected. Email viruses are the ones that are most likely to get inside your system.

The best practice is to not open any email attachments from people you don't know. Email attachments from people you do know should be approached with caution if they're worded strangely, or if you've no reason to expect an attachment from a particular person. And lastly, always keep an updated version of anti-virus software on your computer. A good anti-virus program will not only monitor your system, but will screen incoming emails for suspicious content.

Resource: Wikipedia,
picture taken from:

Thursday, June 18, 2009

How the Sun Shines

What makes the sun shine? how does the sun produce the vast amount of energy necessary to support life on earth?
The Sun shines because it sends out energy in all directions as radiation. This radiation takes the form of light and heat. Almost the same amount of radiation leaves the Sun in all directions. It takes about eight minutes for the light from the Sun to travel to the Earth.
the Sun is an enormous ball of hydrogen and helium, with a few trace elements thrown in. At the surface, the Sun is only about 6,000 Kelvin, but as you drop down within the Sun, the temperatures and pressures rise. By the time you reach the core, the temperatures are more than 15 million Kelvin. And the normally lightweight hydrogen has been crushed together with a density of more than 150 times the density of water.

At these pressures and temperatures, fusion can happen. Inside the core of the sun, two atoms of hydrogen are combined to create helium-4 atoms. This process happens countless times every second. In fact, more than 600 million tons of hydrogen are converted into helium every second. The Sun converts the equivalent of the mass of the earth every 70,000 years.

This releases an incredible amount of energy as photons. These photons are released and then absorbed by gas molecules. And this process happens millions of times during the lifetime of a photon. Amazingly, it takes time for this energy to get out of the Sun. A photon of energy generated at the core of the Sun can take 200,000 years to reach the surface. The light takes hundreds of thousands of years to get from the core to the surface, and then a mere 8 minutes to travel from the Sun to the Earth.

So, the question is change right now, when it will be stop to shine?

just imagine by know, what will be happen.

How Does Rainbow Happen

rainbows appear whenever the sun is visible and there are small raindrops in the sky in the direction opposite the sun. that's why rainbow often appears after rain, because there still has some raindrops in the air, while the sun shining. At any point between the Sun and the water droplets in the air, different wavelengths of light will strike that spot from different droplets. As the angle changes between the observer and the water droplets, so does the frequency of the reflected light, and therefore, the color. That is why rainbows are curved, or circular.
The most spectacular rainbow displays happen when half of the sky is still dark with raining clouds and the observer is at a spot with clear sky in the direction of the Sun. The result is a luminous rainbow that contrasts with the darkened background.
The rainbow effect is also commonly seen near waterfalls. The effect can also be artificially created by dispersing water droplets into the air during a sunny day.

ccasionally, a second, dimmer, and thicker secondary rainbow is seen outside the primary bow. Secondary rainbows are caused by a double reflection of sunlight inside the raindrops, and appear at an angle of 50°–53°. As a result of the second reflection, the colours of a secondary rainbow are inverted compared to the primary bow, with blue on the outside and red on the inside. The dark area of unlit sky lying between the primary and secondary bows is called Alexander's band, after Alexander of Aphrodisias who first described it.

A third, or tertiary, rainbow can be seen on rare occasions, and a few observers have reported seeing quadruple rainbows in which a dim outermost arc had a rippling and pulsating appearance. These rainbows would appear on the same side of the sky as the Sun, making them hard to spot. One type of tertiary rainbow carries with it the appearance of a secondary rainbow immediately outside the primary bow. The closely spaced outer bow has been observed to form dynamically at the same time that the outermost (tertiary) rainbow disappears. During this change, the two remaining rainbows have been observed to merge into a band of white light with a blue inner and red outer band. This particular form of doubled rainbow is not like the classic double rainbow due to both spacing of the two bows and that the two bows share identical normal colour positioning before merging. With both bows, the inner colour is blue and the outer colour is red.

Higher-order rainbows were described by Felix Billet (1808-1882) who depicted angular positions up to the 19th-order rainbow. A pattern he called “rose”. In the laboratory, it is possible to observe higher-order rainbows by using extremely bright and well collimated light produced by lasers. A sixth-order rainbow was first observed by K. Sassan in 1979 using a He Nelaser beam and a pendant water drop. Up to the 200th-order rainbow was reported by Ng et al. in 1998 using a similar method but an argon ion laser beam

information taken from: Wikipedia

Wednesday, June 17, 2009

What is Fire?

Fire is a chemical reaction.

Fires start when a flammable and/or a combustible material with an adequate supply of oxygen is subjected to enough heat and is able to sustain a chain reaction. Fire cannot exist without all of these elements being in place.

A fire needs oxygen and some kind of fuel such as wood, candle wax, or gasoline.

So the fire is not object, but it is a combination of parts and combining in a reaction, while the process is running, the fire is exist.

Tuesday, June 16, 2009

How the Rain Happen?

Rain occurs because of the condensation of water in clouds.
When water evaporates from the earth, it collects in the atmosphere into clouds. When the water in clouds condenses to the point of liquifying, it rains.

The water on earth goes through a cycle when it first exists as vapor in the atmosphere, then, when weather conditions are favorable, it condensates and form clouds which then in turn "break" apart in the form of rain drops. The liquid water on earth flows in rivers, forms lakes and oceans and eventually becomes either frozen in the ice of the poles or evaporates to form more clouds.

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