Hacker News new | ask | show | jobs
by basementcat 512 days ago
For me, an optics analogy appealed to my intuition. A transmission line is analogous to a periodic crystalline material, perhaps a form of quartz. Impedance is analogous to index of refraction; if two materials of differing index of refraction are juxtaposed, some of the light will reflect back. If the indices of refraction match ("impedance match") then there is no reflection and maximum energy transfer takes place.

https://en.m.wikipedia.org/wiki/Refractive_index

3 comments

> Impedance is analogous to index of refraction

That's not just an analogy; impedance is index of refraction, with the same body of modern theory, except that "impedance" derives from the history of analysis of low frequency ("radio") waves whereas "index of refraction" derives from the history of analysis of high frequency ("optical") waves.

Thanks. I found experiments like this [0] helpful to visualize reflections and standing waves, but, like a sibling comment said, although these are similar phenomena and show what happens with the energy inside the wire, I couldn't see why these effects manifested at the electrical level.

[0] - https://youtu.be/1PsGZq5sLrw

Yeah, that's easy to work with so it's a great working model. But as an explanation, it leaves a lot to be desired.

In fact, I'd say it's easier to explain optical refraction with an electrical model than the other way around.