Explain why infrared light is not used to send signals from a phone to a cell tower.

Infrared light is not used to send signals from a phone to a cell tower for several reasons:

1. Limited Range: Infrared (IR) signals have a very limited range. They are typically used for short-range communications such as television remotes or wireless mouse devices. Cell towers, on the other hand, are often miles away from the phone, which is far beyond the range of IR signals.

2. Line of Sight: Infrared signals require a clear line of sight between the transmitter and the receiver. This means that if there is any object blocking the path between the phone and the cell tower, the signal will be interrupted. This is not practical for mobile phones as users often use them indoors or in areas with many obstructions.

3. Interference: Infrared signals can be easily interfered with by other sources of light, such as sunlight or artificial light. This can cause the signal to be lost or degraded, which would affect the quality of the communication.

4. Bandwidth: Infrared signals have a lower bandwidth compared to other wireless communication methods like radio waves. This means they can transmit less data per second, which would slow down the speed of the communication.

For these reasons, radio waves, which have a longer range, can penetrate obstacles, are less prone to interference, and have a higher bandwidth, are used for communication between phones and cell towers.