What+is+a+cell+phone+and+how+do+they+work?

People use cell phones every day of their lives but most people don’t realize that they are just very advanced two way radios. A cell phone is very complicated and took a lot of work to invent. In the 1970s Martin Cooper led the team that made the first cell phone. His team made a complex radio to create the cell phone. Like *CBs and *Walkie Talkies, the first cell phone used invisible *radio waves to communicate. However, the cell phone was more advanced than a CB or walkie talkie. For example, a CB radio only has 40 communication *channels but a cell phone has 1,664 channels. Unlike a CB radio, a cell phone uses two channels to communicate so you can talk and listen at the same time. Cell phones communicate to cell towers so you can drive around a city and talk as the phone communicates to different cell towers. The cell phone communicates like a radio and moves from cell tower to cell tower as it moves. By cell towers that are connected to telephone lines, cell phones can communicate to anywhere a telephone line can. The cell phone can also do much more than help you talk to others. Cell phones now have email, maps, and text messaging and are used by billions of people every day. __Cell Phone paper__ __ Cell Tower __ __Martin Coope__r Figure1- Parts of a cell phone Figure2- Cell tower (receives and sends signals) Figure3- Martin Cooper (The creator of the cell phone)
 * WHAT IS A CELLPHONE AND HOW DO THEY WORK **




 * Cell Phone Fun Facts **

The first cell phone handset weighed over 2 pounds. Now cell phones come in all shapes and sizes. Cell phone usage has grown a lot since 1999. In 1999, 3 out of 10 Americans used cell phones. By 2009, 9 out 10 Americans used cell phones. By 2009, cell phones were used for 6.1 billion minutes per day. By 2011, there were 5.6 billion cell phone subscriptions in the world. Over 70% of the world population now has access to a cell phone.

Cell Phones seem like harmless devices but they could cause brain cancer. Many people talk on the cell phone multiple times a day (it’s their way of communicating), but people don’t realize that they may be causing a higher risk of brain cancer. The radio waves from the cell phone get absorbed by the tissue in a person’s body when people hold the cell phone too close. If this happens too frequently it could cause cancer. Scientist are doing many tests to figure out if cell phones really can cause cancer. It is too early to tell. Some ways to use cell phones more safely are to put the cell phone on speaker or to not use the phone too often.
 * Cell Phone Hazard **

CB radio- A device that sends as well as receives radio signals, but only in a certain area. Walkie Talkie- A device that enables someone or something to communicate from a certain distance Channels- A series of courses that communicate together Radio waves- A invisible wave used for communication
 * Glossary **

National institute of health," Cell Phones and Cancer Risk". 06/18/2012. Web InfoPictures," Fun Facts: Cell Phones". 05/09/ 12. web Hakuna matata, "Who invented the mobile phone". 10/13/10.web
 * Citations **

Woodford, Chris, Collins, Luke, Witchalls, Clint, Morgan, Ben, and Flint, James "Cool

 Stuff and How it Works" New York, DK publishing Peacecraft," How do cell phones work". 9/ 4/12.web

Britannica" Cell Phones". 09/04/12.web/print

"The New book of Popular Science" Volume 6, Grolier, Philipines, 2006. Print