Preparation:

In this activity you will use a remote control such as the one used for a TV or VCR. To start this activity you should learn a little about how the remote control communicates with the TV or VCR. In order to do this, complete these activities and answer the following questions.

1. Most remote controls have a plastic section that is dark but different from the black plastic section that covers the rest of the remote. The signal leaves the remote through this section. Cover this part of the remote control. Does the TV still respond?
2. Usually you can find the place where the signal is recieved. It will have dark material covering it. Does the TV respond when it is covered?
3. Will the TV respond if someone stands between the remote control and the TV? Try several positions.
4. Can the TV be controlled if the signal is transmitted through glass and bounced off a mirror?
5. Based on these results, describe how the signal coming from the remote is similar and different from visible light.

The answers to these questions indicate that a signal is coming out of the remote control which behaves as light does. No light is visible when you activate the remote. However, the remote is sending out a low-energy light signal to communicate with the TV. Most remote controls emit infrared (IR) light, which has an energy that is less than 1.6 eV. When the remote is activated, pulses of infrared light leave the remote control. When this light is received by the device, it is interpreted and the TV, VCR, or CD player responds.