- cross-posted to:
- lemmyshitpost@lemmy.world
- cross-posted to:
- lemmyshitpost@lemmy.world
cross-posted from: https://lemmy.world/post/27589038
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Lol this one was great, thanks for sharing. My partner teaches physics and I do EE on the side, I like rubbing these in her face sometimes.
Simple, all you need is a 6 ohm resistor and a 0.18457216 ohm resistor in series.
No just get a bunch in parallel!
This implies a physicist would do anything practical ever
Ohm no !
And no spherical cows either??
Love how there are so many actual solutions in The comments
But not really. At this level of precision, the heat from electricity passing through it would throw off the actual resistance value.
Bet they’re all engineers.
That’s revolting.
First of all, why are they in the chip aisle looking for resistors? Everybody knows they’re in the bread aisle…
If you’re breadboarding this, you’ve already lost
He’s going to make potato chip resistors to get the right number of course.
Just count the ripples!
Careful, capacitors reduce ripples
I used to make shunt resistors out of a pencil and a piece of paper. Rub pencil all over paper, cut strips to size of required resistance.
EDIT: I mean megaohm resistors not shunt resistors. 20MOhm for DIY theramin.
That’s cool, could you share some photos? The theramin I mean
This is exactly how high precision resistors are calibrated. A laser is usually used to notch out bits of the resistor to tune it after it’s made.
I admire it but also…wtf lol
I made a potentiometer with paper and graphite clay once
Confuses me that anybody would downvote you for this. I’ve made makeshift capacitors out of rolled aluminum foil. It’s dumb, but it worked for what I wanted (triggering a trackpad via stepper motors for testing microcontroller code.) Plus I just wanted to see if it even worked. Life = science experiments.
What’s the significance of that number? It’s less than 0.1 away from tau, but somehow I doubt that’s it…
I can’t be arsed to check but I think it’s 2 pi which is useful when dealing with sine waves.
2 pi is tau, which is what I said it’s less than 0.1 away from, but still not equal to.
For me, it was this video. It came out shortly after I graduated high school, and though I was pretty good at maths, I struggled to really conceptualise the fundamental intuition behind trigonometric functions and the (polar) complex plane. Instead, I was relying on brute memorisation of the unit triangles. Learning about tau and how it relates just instantly caused everything to click with me.
I assumed the number is not significant, figure it’s just supposed to mock the idea that physicists don’t know what tolerances are.
An experimental physicist should know as far as I know meanwhile a real (theoretical) physicist would probably not even touch numbers that have those scary decimals.
There is if you have a potentiometer and a steady enough hand!
U probably need a climate controlled box as well.
Fixed resistors
https://en.m.wikipedia.org/wiki/Resistor
The TCR of foil resistors is extremely low, and has been further improved over the years. One range of ultra-precision foil resistors offers a TCR of 0.14 ppm/°C, tolerance ±0.005%, long-term stability (1 year) 25 ppm, (3 years) 50 ppm (further improved 5-fold by hermetic sealing), stability under load (2000 hours) 0.03%, thermal EMF 0.1 μV/°C, noise −42 dB, voltage coefficient 0.1 ppm/V, inductance 0.08 μH, capacitance 0.5 pF.Quantum based resistors :
https://en.m.wikipedia.org/wiki/Quantum_Hall_effect
Quantum Hall effect →
Applications →
Electrical resistance standards :(…) Later, the 2019 revision of the SI fixed exact values of h and e, resulting in an exact
RK = h/e2 = 25812.80745… Ω.(this is precise to at least 10 significant digits)
Quantum Ampere Standard
https://www.nist.gov/noac/technology/current-and-voltage/quantum-ampere-standard
.
https://www.nist.gov/noac/technology/current-and-voltage(…) Quantum-based measurements for voltage and current are moving toward greater miniaturization (…)
(there also been research for defining a quantum based volt standard)
A 6.2R in parallel with a 2.5K is pretty close.
Add in a 400k and you’re better than most tolerances you can find
