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Name: Karl Twelker
Status: Student
Age: 15
Location: N/A
Country: N/A
Date: N/A

I am just beginning a science fair project on Magnetohydrodynamics used in boat propulsion, and I was wondering what could be done. I came across a site on the Internet that described a device that was an open ended box, with on the top and bottom magnets and the sides electrodes(inside).

The theory was that the electrodes would attract the ions of Cl and Na in the water, and because of the magnetic field and electrical field, the particle would have to move out one end or the other(because of the Right Hand Rule, charged particles must travel perpendicularly to magnetic and electrical fields. Is this true?).

Not quite. A charged particle in an electric field is going to feel an acceleration along the direction of the electric field, and this will remain true whatever else you add to the picture. If that acceleration makes the charge move in a direction perpendicular to a magnetic field, then the charge will feel an additional acceleration, proportional to its speed, in a direction perpendicular to its velocity and to the magnetic field. The direction is given by the right hand rule.

Reverse the directions of the fields and explain what happens in each of the four possibilities.

Tim Mooney

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