From Wikipedia, the free encyclopedia

1. Electricity is the set of physical phenomena associated with the presence and flow of electric charge. Electricity gives a wide variety of well-known effects, such as lightning, static electricity, electromagnetic induction and electrical current. In addition, electricity permits the creation and reception of electromagnetic radiation such as radio waves.
2. electric power where electric current is used to energise equipment; 
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Pollution-From Wikipedia, the free encyclopedia

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Child This article is about the juvenile human

This article is about the juvenile human. For other uses, see Child (disambiguation).
Children swinging
A group of Young Pioneers of China in 2009

Biologically, a child (plural: children) is generally a human between the stages of birth and puberty. [1] [2] The legal definition of child generally refers to a minor, otherwise known as a person younger than the age of majority. [1]

Child may also describe a relationship with a parent (such as sons and daughters of any age) [3] or, metaphorically, an authority figure, or signify group membership in a clan, tribe, or religion; it can also signify being strongly affected by a specific time, place, or circumstance, as in "a child of nature" or "a child of the Sixties". [4]

 All children go through stages of social development. An infant or very young child will play alone happily. If another child wanders onto the scene, he/she may be physically attacked or pushed out of the way. Next, the child can play with another child, gradually learning to share and take turns. Eventually, the group grows larger, to three or four children. By the time a child enters kindergarten, he or she can usually join in and enjoy group experiences.^[8]

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Computer Computer technology"

A computer is a general purpose device that can be programmed to carry out a set of arithmetic or logical operations automatically. Since a sequence of operations can be readily changed, the computer can solve more than one kind of problem.

Modern computers based on integrated circuits are millions to billions of times more capable than the early machines, and occupy a fraction of the space. [2] Simple computers are small enough to fit into mobile devices, and mobile computers can be powered by small batteries . Personal computers in their various forms are icons of the Information Age and are what most people think of as "computers." However, the embedded computers found in many devices from MP3 players to fighter aircraft and from toys to industrial robots are the most numerous.

 

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Pollution From Wikipedia, the free encyclopedia

Pollution is the introduction of contaminants into the natural environment that cause adverse change. [1] Pollution can take the form of chemical substances or energy, such as noise, heat or light. Pollutants, the components of pollution, can be either foreign substances / energies or naturally occurring contaminants. Pollution is often classed as point source or nonpoint source pollution

.Air pollution has always accompanied civilizations. Pollution started from prehistoric times when man created the first fires. According to a 1983 article in the journal Science, "soot found on ceilings of prehistoric caves provides ample evidence of the high levels of pollution that was associated with inadequate ventilation of open fires." [2] Metal forging appears to be a key turning point in the creation of significant air pollution levels outside the home. Core samples of glaciers in Greenland indicate increases in pollution associated with Greek, Roman and Chinese metal production, [3] but at that time the pollution was comparatively small and could be handled by nature.

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