If you read the last links, you'll realize that RFID seems really complicated. It is, and we probably shouldn't be messing with it in a 100-level class ;-) However, given that you are all exceedingly clever, I think we'll be OK.
As a sort of warm-up project, while we're figuring out how RFID workst, we'll first consider how shoplifting tags work. Not, and I cannot stress this enough, how to defeat them, but how they are implemented.
Two common types of anti-shoplifting measures, implemented in DVDs and books for example, essentially use magnetic induction and resonant circuits, which we'll get to next week. If you can figure out how these work, the basic idea behind RFID is not so far off. Another topic we'll touch on along the way to RFID is wireless power transmission, or how to charge your phone without cables. Ostensibly less potential for misuse, similar physics.
The main point here is that I think these things are worth understanding, highly relevant, and involve some nice applied physics. We will not delve into the nefarious uses of what we learn, just as we did not really discuss practical weaponry in mechanics. Learning enough to figure out what's going on around us is a Good Thing, learning how to use that knowledge is another.
Vonnegut had an interesting take on this in Timequake (see the top of the page), which I thought made a good point if a bit too extreme. We'll focus on physics, and leave the philosophizing to more qualified departments.
Anyway: just fair warning, I'm not going to help you figure out how to read other people's IDs, but I will help you figure out that the relevant technology is not in fact magic, but merely clever, Clarke's 3rd law notwithstanding.
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