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Cathode Ray

Start with the video, then use the science notes and recommended parts below to follow the idea behind the build.

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How it works

What this project is testing.

A cathode ray tube makes electrons visible. In a low-pressure tube, high voltage pulls electrons away from the cathode and sends them across the glass where the beam can glow.

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The experiment demonstrates that the ray is made of charged particles, not just light. Bring a magnet nearby and the beam bends because moving charges feel a sideways magnetic force.

F = q v \times B

A magnetic field pushes moving charged particles sideways.

\frac{1}{2} m v^{2} \approx e V

Voltage gives electrons kinetic energy as they accelerate through the tube.

Recommended parts

Products used in this project.

Affiliate links may earn Keystone Science a commission. Match ratings, values, sizes, polarity, and safety requirements to your own build before buying.

DEVMO DC 3V-6V to 400kV 400000V Boost Step-up Power Module High-Voltage Generator

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LOVIMAG Strong Neodymium Disc Magnets with Double-Sided Adhesive

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BACOENG 3 Gallon Tempered Glass Lid Vacuum Chamber with Pump, Stainless Steel Degassing Chamber Kit for Resin, Silicone, Epox

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TUOFENG 30 awg Wire Solid Core Hookup Wires-6 Different Colored Jumper Wire 100ft or 30m Each, 30 Gauge Tinned Copper Wire PV

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J-B Weld 8265S Original Cold-Weld Steel Reinforced Epoxy - 2 oz.

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J-B Weld Original Cold-Weld Two-Part Epoxy

Project files

Prints, kits, and downloads.

Diagrams, printable files, kits, or companion downloads will appear here when they are ready to use.

Coming soon

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