So here's my idea.The purpose is for children's safety. A child will have to wear a watch wherein it will send off signals continuously and when the receiver which is inside an extension receives the signals emitted from the child's watch it will trigger the outlet to switch off then the appliances plugged in that extension will be off. As for the extension I'm gonna put a relay circuit inside an extension wherein any appliances could be plugged in.I am planning on using Bluetooth for the connection wherein when it is paired, it will trigger the relay in the extension to switch off the electricity. May I ask on how can I set a specific conditions depending on the distance using Bluetooth module. Is it even possible to measure the distance using bluetooth?
I'm not sure about getting any sort of distance from a bt module.. (I suppose it would depend on the specific module?)
I have only played with the HC-05 type modules.. (which I thick are roughly 30 feet or so limit?)
anyways.. can you do a query/response type of approach? and if you dont get a 'response'.. you can assume you are out of range? and then trigger relay?
xl97:
I'm not sure about getting any sort of distance from a bt module.. (I suppose it would depend on the specific module?)I have only played with the HC-05 type modules.. (which I thick are roughly 30 feet or so limit?)
anyways.. can you do a query/response type of approach? and if you dont get a 'response'.. you can assume you are out of range? and then trigger relay?
Well HC-05 specifically is my bluetooth module. 
Umm Can I use other module besides bluetooth. I think it's hard to use bluetooth since we are gonna need to auto connec it and as well as get a certain distance. Could I possibly use RFID?
no.. I dont think so....(re:RFID)
from what I know from playing around with my MiFaire RFID set-up is that the range is extremely limited. were talking 'near' contact only... so they would have to lift something up off it/away from it and the relay would trip.. There may be other set-up they have a it more range, but not sure how large really and at what prices. (do you need something mobile?)
what 'IS' the limit you are looking at? you're not really telling any real specs you are looking to build for/toward. 
I would google all these topics yourself to make sure I am even correct... I am an noobie myself, and these comments are just from my limited reading and mostly knowledge/results from playing around with these components (ordered through ebay).. lol..
I'm a sure someone before you has wanted to know the distance using bluetooth.. (maybe with another component as well?) see how they approached and solved it.