I was watching The Simpsons the other day and there was a scene of Homer as a child sitting much too close to a TV that had the brand name “Radiation King.” This got me to thinking of an old TV I had in my room when I was a tyke. I presumed the TV was a particularly evil TV because it would glow long after it was turned off. I also happened to find out that if I put my hand on the TV (when it was turned off) while the lights were on, then removed my hand after turning off the lights it would leave the image of my hand glowing on the TV. Why did this happen? Is that radiation? Should I be concerned that my own “Radiation King” hurt me a bit? It was also good at shocking the piss out of me when I turned it on…
No, what you wre observing was common in older color and black-and white TVs, and is a phenomenon known as phosphorscence. Specifically electrophosphorescence. It’s a property of some substances which can absorb electromagnetic energy and re-radiate the energy on another wavelength over a period of time. The specific reason it happened on TV screens is the static that would build up on the surface creates an electric field whose energy can knock electrons in the screen’s phosphors (the chemicals that glow when the electron beam hits them) to a higher orbital, and when the electron jumps back to its ground state, a photon is emitted. The reason your hand leaves a hand-shaped dark area is that your body is discharging the static at ponts where your hand contacts the screen, removing the energy source driving the phosphorescence.
It’s photonic radiation! :eek:
Now you are just making that part up, Q.E.D. Anybody can produce this effect with any TV or monitor screen and a flashlight. Leave the TV/monitor off in a dark room, place your hand on the screen, shine the flashlight at your hand for 30 seconds or so (I suggest closing your eyes to preserve your light sensitivity), then turn off the flashlight and look at the screen. What you are seeing is a shadow of your hand, produced by the phosporescence of the screen absorbing energy from the flashlight. Has nothing to do with static charge.
Just reverse the polarity and you’ll be just fine.
Fear Itself: Yes, but to do it WITHOUT a flashlight requires the effect Q.E.D. described.
I can’t make my TV do it anyway. The latency period of the phosphors is way to short. It certainly won’t do it in room light, and a flashlight has to be held right up to the screen. I remember my grandma’s old B&W TVs doing this in a pronounced manner though. I’ll admit room light might contribute to the effect, as well, but I was always told it was the static (which made sense, as the phosphors are electrically excited by having electrons slammed into it).
In a dark room, turn the tv off when it’s been on for at least a half hour. Touch the screen lightly and you will hear little ‘pops’, like tiny little static electricity sparks, though they don’t hurt. If you haven’t dusted recently, the dust will actually poof away from where you touch, leaving little craters of cleanliness.
Also, if you draw your finger along on the screen you scan leave trails that glow for a short while before fading out.
(Simple minds are amused by simple things, oh yes.)
Yeah, It’s fun to do these things on big screen tv’s also. Lots of room to mess around with.