Uses and working of the following

fax machinecell phone

photo phonecomputer

FAX MACHINE

Working of a fax machine

• A fax machine (from the word facsimile or copy) is designed for sending copies of documents over phone lines to anywhere in the world. They were in use long before the introduction of PC's, the development of the World Wide Web, or the widespread use of Email. A lot of businesses and individuals still use them because they are simple, cheap, and don't require a PC or an internet connection.

• Basically a Fax machines is three devices in one.

• First is a document scanner, usually monochrome, and usually sheet-feed.The second is a printout device, also sheet feed with an inkjet or laser print engine, or roll feed for thermal paper.Joining them together would be small dedicated purpose computer and modem.They look very similar to a home-type inkjet printer. You put your documents to be sent in one tray, enter the phone number of the fax machine you wish to send the documents to and press Send. The machine draws the documents through it, scanning them and saving digital images into memory. The machine dials the number, waits for acknowledgment from the fax machine on the other end then transfers the images using different frequency tones to translate varying shades of dark and light.

Uses of fax machine• A fax machine is used to send documents instantly to

another fax machine through a standard telephone line. Most fax machines can also be used to make copies of documents and some can also be used as a computer printer or scanner.

• A fax machine can send and receive documents that include text and images simply at the push of a button. The advantage of a fax machine over an email is that it takes a physical document from the sender and transmits it in physical form to the receiver.

• There is no need to scan the document before sending it, nor do you have to print it off when you receive it - both of which you would have to do with e-mail. This is because the fax machine basically is a scanner, modem and printer all in one unit, which cuts down on your need for all of these machines.

Cell phone

CELL PHONE• Millions of people in the United States and around

the world use cellular phones. They are such great gadgets -- with a cell phone, you can talk to anyone on the planet from just about anywhere!

• These days, cell phones provide an incredible array of functions, and new ones are being added at a breakneck pace. Depending on the cell-phone model, you can:

• Store contact information• Make task or to-do lists• Keep track of appointments and set reminders

• Use the built-in calculator for simple math

• Send or receive e-mail

• Get information (news, entertainment, stock quotes) from the Internet

• Play games

• Watch TV

• Integrate other devices such as PDAs, MP3 players and GPS receivers

But have you ever wondered how a cell phone works?

• To start with, one of the most interesting things about a cell phone is that it is actually a radio -- an extremely sophisticated radio, but a radio nonetheless. The telephone was invented by Alexander Graham Bell in 1876, and wireless communication can trace its roots to the invention of the radio by Nikolai Tesla in the 1880s (formally presented in 1894 by a young Italian named Guglielmo Marconi). It was only natural that these two great technologies would eventually be combined.

• When a mobile phone is switched on, it finds and connects to a nearby mobile phone base station. Computers in the base station check that the phone is allowed to use the network. The base station covers what is called a cell and a phone can move between different cells, but will only ever communicate with one cell at a time. This is why mobile communications are sometimes called cellular communications.Once connected to a cell, the mobile phone can make calls. Because the network knows that the phone is connected to that particular cell, it can also route calls to the mobile phone. Sometimes the radio connection to the cell is lost, for example when you go underground. This means the phone cannot make or receive calls until the connection is made again.

PHOTO PHONE• On June 3, 1880, Alexander Graham Bell transmitted the

first wireless telephone message on his newly invented "photophone." Bell believed the photophone was his most important invention. The device allowed for the transmission of sound on a beam of light. Of the eighteen patents granted in Bell's name alone, and the twelve he shared with his collaborators, four were for the photophone.

• Bell's photophone worked by projecting voice through an instrument toward a mirror. Vibrations in the voice caused similar vibrations in the mirror. Bell directed sunlight into the mirror, which captured and projected the mirror's vibrations. The vibrations were transformed back into sound at the receiving end of the projection. The photophone functioned similarly to the telephone, except the photophone used light as a means of projecting the information, while the telephone relied on electricity.

• Although the photophone was an extremely important invention, it was many years before the significance of Bell's work was fully recognized. Bell's original photophone failed to protect transmissions from outside interferences, such as clouds, that easily disrupted transport. Until the development of modern fiber optics, technology for the secure transport of light inhibited use of Bell's invention. Bell's photophone is recognized as the progenitor of the modern fiber optics that today transport over eight percent of the world's telecommunications.

COMPUTER• To accomplish a task using a computer, you need a

combination of hardware, software, and input.• Hardware consists of devices, like the computer itself, the

monitor, keyboard, printer, mouse and speakers. Inside your computer there are more bits of hardware, including the motherboard, where you would find the main processing chips that make up the central processing unit (CPU). The hardware processes the commands it receives from the software, and performs tasks or calculations.

• Software is the name given to the programs that you install on the computer to perform certain types of activities. There is operating system software, such as the Apple OS for a Macintosh, or Windows 95 or Windows 98 for a PC. There is also application software, like the games we play or the tools we use to compose letters or do math problems.

• You provide the input. When you type a command or click on an icon, you are telling the computer what to do. That is called input.

How They Work Together• First, you provide input when you turn on the computer. Then

the system software tells the CPU to start up certain programs and to turn on some hardware devices so that they are ready for more input from you. This whole process is called booting up.

• The next step happens when you choose a program you want to use. You click on the icon or enter a command to start the program. Let's use the example of an Internet browser. Once the program has started, it is ready for your instructions. You either enter an address (called a URL, which stands for Uniform Resource Locator), or click on an address you've saved already. In either case, the computer now knows what you want it to do. The browser software then goes out to find that address, starting up other hardware devices, such as a modem, when it needs them.

• If it is able to find the correct address, the browser will then tell your computer to send the information from the web page over the phone wire or cable to your computer. Eventually, you see the web site you were looking for.If you decide you want to print the page, you click on the printer icon. Again, you have provided input to tell the computer what to do. The browser software determines whether you have a printer attached to your computer, and whether it is turned on. It may remind you to turn on the printer, then send the information about the web page from your computer over the cable to the printer, where it is printed out.