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Q & A: wavey vision?

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Most recent answer: 10/22/2007
Q:
I would like to know the reason why when i use my electric toothbrush my vision is wavey but only when i look at my computer or television, i know it has to do with the refresh rate but is it also affecting my vestibular ocular reflex? would i get dizzy if it was?
- Crystal Martin (age 13)
New Zealand
A:
Since nothing but the CRT (cathode ray tube) screens gets wavey, you can be confident that your vision is just fine. The effect is purely electromagnetic. The toothbrush is giving off some E-M pulses which affect the paths of the electrons in the the CRTs on their way to the screen.

Mike W.

Another thing which could be happening is that your electric toothbrush is making your whole head vibrate just a little bit. If the vibrations of your head and the refresh rate of the screen are slightly different (or are slightly different from a multiple of each other), then you will see slow wiggles in what the screen looks like. We've already covered the case where you blow a raspberry (a good old "Bronx Cheer") at a computer screen (search for "raspberry" in our answers). This produces nice wavey patterns when I do it with my screen sitting in front of me.

Mike tells me he tried turning on an electric toothbrush next to a computer monitor and saw wavey patterns. If you just hold the toothbrush close to the monitor without sticking it in your mouth, the effect would have to be due to electromagnetic pickup. Check to see if the effect gets stronger as you wave the toothbrush closer to the monitor. I don't have an electric toothbrush so I couldn't try it myself.

Regardless of the origin of the waviness, you certainly can get dizzy or get a headache by doing this. The effect should wear off when you stop.

Tom

(published on 10/22/2007)

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