Here is a new app on Uses of Radioactivity. I hope you find it useful ☢️ #iTeachPhysics www.drjonesphysics.com/rad-uses

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It happened today in Chicagoland! Cosmic Pathways Chicago! #Physics #Astronomy #ITeachPhysics cosmicpathways.org/2026/10/17/c...

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One thing I think is cool is that a steeper pitch angle both increases the "length" of the film ribbon and also decreases its width and thus cross-sectional area, for a double-strength effect on R. I keep trying to write a problem about this for my 11th graders but it's too fiddly for them.

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There's a great book called Open Circuits where they do cutaways of a bunch of electronics components, commercial resistors included. IIRC, the insides of the blob resistors are spirals of material etched to modify both the length and width of the spiral to get the right resistance.

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Yes, most resistors in use today are carbon film resistors with a thin layer of graphite on an insulating core. A helix is etched along the graphite turning it into a wound ribbon. R is customized by the film thickness and pitch angle of the etch. A nice explainer here: eepower.com/resistor-gui...

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