Expert: Apurv - 9/8/2009

Question
Wasn't too sure of the category for this.My question is:   Is it possible to send a radio signal or whatever to a small device buried under the ground that has no power but yet can easily be detected or made to send a signal back.( Range of say 200 yards to 1/4 of a mile ).

Answer
How can you expect a device to function without power ?
Any device/circuit will require power to operate, transmitting signal is still a second thing.
So no electronic device can be used.

You can search for the answer in chemistry. Like the device has some kind of chemicals that can be detected from the required range.