Plastics

Plastics are cross linked polymers and are very tough. Lac is a natural plastic, chemical plastic can be of two types :

(i) Thermoplastic Plastics : These are the polymers which can be easily softened repeatedly when heated and hardened when cooled with little change in their properties.

Examples : Polyethylene, Polyatyrene, Teflon etc.

Plastic Sheet

(ii) Thermosetting Plastics : These are the polymers which undergo permanent change on heating. On heating they undergo extensive cross linking in moulds and become hard and infusible therefore, they can not be reused.

Examples : Bakelite, Glyptal, Terrylene etc.

Bakelite Handle

Theory of Colors

Color : Color is the sensation perceived by the rods in the eye due to light.

Primary Colors : The spectral colors blue, green and red are called primary colors because all the colors can be produced by mixing these in proper proportion.

»  Red + Green + Blue = White




Secondary Colors : The colors produced by mixing any two primary colors is called a secondary colors. There are three secondary colors Yellow, Magenta and Cyan as :

»  Green + Red = Yellow

»  Red + Blue = Magenta

»  Blue + Green = Cyan




When the three secondary colors are mixed, Black color is produced.

»   Yellow + Magenta + Cyan = Black

Countries and their Currency

»»   Austria       :     Shilling

»»   Bulgaria     :     Lev

»»   Cuba         :     Peso

»»   Denmark   :     Danish Krone

»»   Ghana       :     Cedi

»»   Hungary    :     Florint

»»   India         :     Rupee

»»   Japan        :     Yen

»»   Nigeria      :     Naira

»»   Poland      :     Zloty

Image of Indian Rupee Symbol

Association of Places : World Volume II

»»  St. Helena : Napoleon Bonaparte

»»  Mecca : Prophet Muhammad

»»  Pearl Harbour : Japan's attack during World War II

»»  Trafalgar : Nelson

»»  Crosica : Napoleon Bonaparte

World Wide Web (WWW)

The World Wide Web (WWW) is the perhaps the most important component that moved the internet from scientists and research organizations to people's homes.

World Wide Web (WWW)

It offers smooth and easy to use graphical interface to access information available on internet and it is considered as synonymous of internet.

The WWW is distributed file management system with programs to access and send information.

The clients to WWW are internet browsers that help to connect to a website server, request a web page and format the received content for display.

The fundamental unit of web page. The web page is a text document developed using HTML that contains links to other web pages, graphics and audio files, and other internet services such as Email.

Web pages reside on web server and can be accessed with the help of internet browsers. Some of the popular internet browsers are : Apple's Safari, Google Chrome, Opera, Netscape etc.