The Rail Gunaka the Slide-wire Generator

Maria Chiara Simani (UCR ALPHA Center)

& Owen Long (UCR Department of Physics)

Copernicus SSI 07 - Follow-up, Nov. 6th 2007

Slide-wire generator: How does it work?

• A changing magnetic flux creates an electricfield and vice versa

Examples you already know:

• Speakers/microphone• Wind-powered generator• Seismometer

Slide-wire generatorB field out of screen

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F F

Area becoming larger => increasing magnetic flux

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F−

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Area becoming smaller => decreasing magnetic flux

Slide-wire generatorUnfortunately, induced voltage too small to bedirectly detected with PASCO probe.

Some options:

• Build amplifier to increase signal (instructionsare available on the Seismometer Web Pages)• Buy sensitive multimeter• Add more magnets to increase B

Rail gun and magnetic forceB field pushes (sideways!) on moving charges.

m

Mass on the end of a ropeswinging in a circle.

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Negative charge moving in a Bfield coming out of screen.

B pointing outof screen

Rail gun and magnetic force

The Aurora: charged particles fromthe solar wind spiral along theearth’s B field lines. Collisions withatoms in the atmosphere excite theelectrons, which emit light when thede-excite to lower energy levels.

B fieldlines

Charged particlesfrom solar wind

Rail gun physics

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Battery

B field into screen

B field into screen

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F

Battery drives a current through the sliding bar.The moving charges inside the bar get pushedsideways by the magnetic force.

Rail gun parts and tools

Parts list• Section of 2x4• Screws & washers• Metal coat hanger• 1 or 2 6V lantern batteries• Strong magnets• Aluminium (not steel!) tube• Alligator clips

Tools list• Drill for drilling holes in 2x4• Screw driver