plz tell me about the working of t.v. remote?

Question

what's in it's rays. why there is limited distance to control it??

Answer 1

TV remotes use near infrared (IR). Near IR means infrared with wavelengths just a little longer than visible light. The visible light spectrum goes from 400 to 700 nano meters (corrected a day after answered). The IR for remote control is typically closer to 850 nano meters.

The range is limited because of the inverse square law for the propagate of any sort of electromagnetic radiation. This means that when the signal has traveled 8 meters it is only 1/64 as intense as it was after only 1 meter. The typical remote control system can operate up to about 8 meters only but for the intended application this is good enough.

The other limitation is that the signal travels line of site only (just like visible light). One can bounce the signal off a wall or ceiling (just like visible light).

For more information and more links see:
http://www3.telus.net/danpeirce/robot/IR/

Answer 2

It uses an infra red LED to send out a very low bit rate pulsed signal to a receiver in a TV which desodes the signals and adjusts the TV. You cannot see the infra red; it's too low a frequency but if you aimed into your video camera and pressed the remote, you could actually see the LED light up.