Tesla CD Turbine At The Science Fair

Spinning things are fun! This Tesla CD Turbine goes to the home-school Science Fair with Mrfixitrick's worthy assistant Rowan, and puts on a fun display for folks.

Rowan demonstrates the magnetic Tesla CD Turbine he built, and Mrfixitrick explains how the recirculating fluid system works.

In one of the strangest magnetic behaviours you will likely see, a magnetic ball is shown revolving counter to the direction of rotation of the turbine.
Can you figure out why this happens?

Rowan does a great job demonstrating, and it's one of the most popular booths at the Science Fair.

For more cool experiments with the Tesla CD Turbine, see my SinkScience playlist and more on my site. http://www.youtube.com/view_play_list?p=DBEC3A3C414EB39F

Check out how a new understanding of magnetism will radically change our world, presented by nuclear engineer Mehran Keshe: http://www.youtube.com/watch?v=wtf5bp76ArE

Buy magnets from K&J Magnetics here:
http://www.kjmagnetics.com/default.asp?PARTNER=mrfixitrick

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[geekwes2]

what type of magnets did you use: blocks, spheres, or discs?

[MrfixitRick]

@geekwes2

We used 1/32 inch thick x 1/4 inch discs as spacers between the CD discs. We also used 1/2 x 1/2 inch neodymium cylinder magnets as the top drive magnets.

[MarkRiverbank]

From your instructables, it appears you are orienting the magnets so that the polarity is the same direction for all of them. What if you alternated the polarity of the magnet stacks [of the 6 stacks, 3 would be north, 3 south], could you get an alternating magnetic field and from there generate electricity?

I believe Tesla's original turbine did not use magnets at all. Someone could build a similar cd turbine using small washers instead couldn't they? [minus the cool rolling ball effect]

[MrfixitRick]

@MarkRiverbank

Yes, alternating magnets would be better for generating electricity. It is problematic to use alternating magnets as a magnetic drive, however.

No supermagnets in Tesla's Turbine, but it requires a shaft, bearings and shaft seals mounted in a strong case in order to get the power out. A mag drive doesn't need these things!

Washers could work as spacers between discs along with drive magnets, perhaps.

[dlchambers]

I'd guess it goes backwards because the turbine magnets pull the bottom side of the ball in the direction that the turbine rolls, causing the ball to spin as if it were actually touching the top CD () that is, the ball's bottom surface moves in the same direction as the turbine). But because the ball is touching the plexi plate, friction causes the ball to move in the opposite direction. Cool how the magnets keep the ball from flying off the plate - sort of like a satellite in Earth orbit.

[fancytableshoes]

Try it with a flat magnet - won't happen. The ball is a magnet, right (not just magnetic steel)? What you're seeing is due to inertia. At slow speeds, the ball is not rolling. It is coupled to a magnet below and simply dragged around. At a certain speed, the lower magnet will outpace the ball, pulling the ball's magnetic axis off vertical, setting it spinning (rolling) about it's own axis. In a perfect world the ball would just sit and roll in place - friction gives it forward motion.

[fancytableshoes]

Try it with a flat magnet - won't happen. The ball is a magnet, right (not just magnetic steel)? What you're seeing is due to inertia. At slow speeds, the ball is not rolling. It is coupled to a magnet below and simply dragged around. At a certain speed, the lower magnet will outpace the ball, pulling the ball's magnetic axis off vertical, setting it spinning (rolling) about it's own axis. In a perfect world the ball would just sit and roll in place - friction gives it forward motion.

[retrorecycler]

I'll bet it goes backwards because it takes a shorter time to reach the magnetic field then if it were following the magnets.

[PerfectParasite]

You should try a tesla turbine only using two magnets. I think that it would generate an interesting affect for the ball.