Hi, I am almost completely ignorant on any Physics beyond the high school level. Not proud of it, but it is a fact. But I am curious about this: While at a bookstore, I set off the RFID detector. I found out, by trial and error, that (something in) my wallet was setting it off, but not clear on precisely what. The security guy deactivated my wallet at this point , and then the wallet stopped setting the alarm off. **BUT** a few days afterwards, the problem reoccurred, i.e., my wallet set off the RFID alarm again . This seems to imply that something I did in the meantime, after deactivating up to the second alarm, may have reactivated the RFID signal, or possibly some chip in my wallet ( I don't think the one in my shoulder was setting things up --ha-ha). What possible explanation is there for this, assuming the alarm is working reasonably well ( which does seem to be the case.) Thank You in Advance.