Magnetism and Movies
by Ann Bartkowski
Last weekend I saw Michel Gondry’s new film, Be Kind Rewind. In this movie, Jack Black’s character becomes magnetized after being electrocuted and subsequently erases all of the VHS tapes in a video store with his body’s new electromagnetic properties.
Thanks to Paul D., I understand that even though electricity and magnetism go together like American Gladiators and steroids, this integral plot detail wouldn’t physically happen in real, non-movie, life. However, the movie left me wondering…is any part of that series unfortunate events even remotely possible? How much electricity would need to be surging through a human body in order to create a magnetic field strong enough to erase a tape? Could a human live through it? And for that matter, does Jack Black have a greater likelihood of becoming a chick magnet or an electromagnet?
Since our bodies are composed of a lot more water than iron, we can be diamagnetic like that frog, but not ferromagnetic. And ferromagnets are the only things that can become permanently magnetized after an electrocution. So Jack Black’s character had a pretty strong magnetic field around him during the ridiculous scene when he was being electrocuted, but not afterwards when he walked back into the video store.
So what if he happened to have been touching a blank tape at the exact moment he was electrocuted? I did some research (thanks, slate.com!) and found out that pretty much you need a current of several thousand amps coursing through your body to generate a magnetic field strong enough to erase the tape you are touching. To put that in perspective, electric chairs only zap you with around 5 amps, so becoming a magnet strong enough to erase a tape would have to be your last feat before you died…
Unless, of course, you were struck by lightening while holding your VHS tape. Although lightening carries more than enough current to demagnetize your tape, about 80 percent of people live through their lighting strikes. Not that I’d recommend trying this or anything. I do recommend you see this movie though, cuz it’s really funny (like Kristin and Marcus dancing) and I think Explainers would appreciate the creativity and imagination used to recreate the blockbusters that got erased.