Recent media attention has focused on a possible link between cell phone use and brain
Cell phones operate with radio frequencies,a form. of energy located on the electromagnetic spectrum between FM radio waves and the waves used in microwave ovens,radar,and satellite stations.Cell phones do not emit ionizing radiation,the type that damages DNA and is known to have the ability to cause cancer.
Cell phone technology works on a system of geographically separated zones called"cells".Each cell has its own "base station" that both receives and emits radio waves.When a call is placed from a cell phone,a signal is sent from the cell phone antenna to that cell's base station antenna.The base station responds to the cell phone signal by assigning the phone an available RF channel.When the RF channel is assigned,radio signals are simultaneously received and transmitted,allowing voice information to be carried between the cell phone and the base.The base station transfers the call to a switching centre, where the call can be transferred to a local telephone carrier or another cell phone.
6.There has existed argument about the link between cell phone and brain tumor()
7.The rapid growing number of cell phone users has been a great concern in the US()
8.The 3rd paragraph tries to prove that cell phones do not cause brain cancer()
9.A switching centre is needed when we make a call through cell phone()
10.The topic of the passage is about cell phone and cancer.()