Re: stoboscopic eyes

[palmer@sfu.ca (Leigh Palmer)]

> Looking at a ripple tank and introducing using a stobe to determine
> frequency, the discussion went to seeing wagon wheels in movies seeming to
> roll backwards. Students maintain that they have seen this in cars with
> naked eye. I don't inderstand the mechanism of how that would happen, yet I
> in retrospect, I think I have seen it, too. Any ideas?

If you watch wheels illuminated by mercury vapor lamps or fluorescent
lights you will be watching them in a 120 Hz stroboscopic illuminant.
(I presume U.S.A.) Could that be the source of your observation?

Leigh