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Registered Member #834
Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
A curious experiment, requiring a simple HV DC source: Another:
My reproductions:
I used a flyback power supply. Not much voltage required. About 10 kV at most. Insignificant current. Works with an electrostatic machine too, but the voltage may be too high. Note that the spinners are symmetrical. They don't spin without the glass pots.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Hi Antonio,
That's very interesting experiment, and it's puzzling me why candle light affects it so much, since it produces relatively little UV and photoelectric effect should be insignificant... I can't figure out what do glass jars to to help either.
Could you perhaps try laser or led light of various wavelengths (infrared, visible and UV) and film the results for us?
Registered Member #834
Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
Marko wrote ...
Hi Antonio,
That's very interesting experiment, and it's puzzling me why candle light affects it so much, since it produces relatively little UV and photoelectric effect should be insignificant... I can't figure out what do glass jars to to help either.
Could you perhaps try laser or led light of various wavelengths (infrared, visible and UV) and film the results for us?
Marko
I think that this is not effect of the light, but of the ionized air generated by the flame. The points on the spinner corners deposit charge on the internal surface of the glass, but the glass is not a perfect insulator, and soon all the pot is charged and at the same potential of the spinner, impeding more current flow. With the flame close, charge leaks from the pot to the air, and the areas close to the spinner corners become more charged than the surrounding area, repelling the corners. As the spinner rotates, there is always more charge where the points just passed than just ahead of them, causing continuous torque on the spinner. A plate of glass inserted between the candle and the spinner stops the rotation. The device doesn't move if exposed to the Sun. The current through the device when spinning is a fraction of uA only. If not useful for anything else, it is a quite efficient electrostatic motor.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
I think I remember seeing an experiment similar to this in a Victorian book of the 1890s.
In the old book, I think the spinner was in the form of a swastika, and I guessed that it was the ionic wind from the ends of its arms that was pushing it round in a circle.
But the forces acting on your spinner do not seem so simple.
Registered Member #834
Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
Proud Mary wrote ...
I think I remember seeing an experiment similar to this in a Victorian book of the 1890s.
In the old book, I think the spinner was in the form of a swastika, and I guessed that it was the ionic wind from the ends of its arms that was pushing it round in a circle.
But the forces acting on your spinner do not seem so simple.
Yes, the spinner with curved points is a classical demonstration device. One of these spinners mounted as the symmetrical spinner in this experiments, in a glass pot, turns too, exactly as the symmetrical spinner does, but always in the same direction, requiring much less power than in plain air, and only when the glass pot is touched or a candle is put close to it.
Separating the candle from the spinner with a glass plate stops the rotation:
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Experiments with "enclosed spinners"
