Sorry but that is incorrect when the wire forms a coil. A typical DC motor when running draws 1/4 or less than Ohm’s law would calculate due to both inductance and back EMF, and your design will do the same.

Bob

My point is ... at the atomic level, ohms law is always the same. When you say, "A typical DC motor when running draws 1/4 or less than Ohm’s law would calculate due to both inductance and back EMF" - surely if those factors could be included in your calculations, then your calc's would be more accurate. My point is that ohms law is always a LAW and when an electron is moving through a conductor, ohms LAW is always there.

OK, here it is in spreadsheet form.

Thank you, I'll play with the spreadsheet soon. My laptop issues turned into a disaster, rendering it irreparable so I ordered a new laptop which should be here this coming Wednesday. I almost got 10 years out of the one that died which is pretty darn good if you ask me.

 

I almost got 10 years out of the one that died which is pretty darn good if you ask me.

It is! My MacBook is hitting ten this year. It gets several hours of use every day. It's got a cracked screen (invisible while in use), a few dead keys, and is running an unsupported OS version. If it makes it through 2021, I'll consider it a miracle. The new models coming along are getting rave reviews, so that should soften the blow.

 

"A typical DC motor when running draws 1/4 or less than Ohm’s law would calculate due to both inductance and back EMF" -

There is no blanket figure as the current all depends on the applied load, when running totaly off load, the current is minimum throughout the whole RPM range.
Max.

 

It is! My MacBook is hitting ten this year. It gets several hours of use every day. It's got a cracked screen (invisible while in use), a few dead keys, and is running an unsupported OS version. If it makes it through 2021, I'll consider it a miracle. The new models coming along are getting rave reviews, so that should soften the blow.

My Toshiba Satellite 2400 is over 18 years old and still in use running WIN XP.

 

My Toshiba Satellite 2400 is over 18 years old and still in use running WIN XP.

Wow, 18 years on a laptop is ... unusual.

 

Wow, 18 years on a laptop is ... unusual.

I didn't tell you about my PC clone and Apple Macintosh that are both over 35 years old.

 

I didn't tell you about my PC clone and Apple Macintosh that are both over 35 years old.

I made a concerted effort to empty my basement "museum", including an old Apple IIe. Oldest box is now a G3. I kept it because it had my last floppy drive, and I needed to go through my old discs before selling them. (Amazingly, discs are worth as much or more than the old computers.)

 

My point is ... at the atomic level, ohms law is always the same. When you say, "A typical DC motor when running draws 1/4 or less than Ohm’s law would calculate due to both inductance and back EMF" - surely if those factors could be included in your calculations, then your calc's would be more accurate. My point is that ohms law is always a LAW and when an electron is moving through a conductor, ohms LAW is always there.


Thank you, I'll play with the spreadsheet soon. My laptop issues turned into a disaster, rendering it irreparable so I ordered a new laptop which should be here this coming Wednesday. I almost got 10 years out of the one that died which is pretty darn good if you ask me.

At the atomic level like in semiconductors, ohms law is not a universal law. In fact most of the electrical responses to energy matter interactions in the universe DON'T conform to Ohm's law. Internal and external physical characteristics must remain exactly constant for it to be true. For example, Tungsten doesn’t obey Ohm’s Law.

 

It is! My MacBook is hitting ten this year. It gets several hours of use every day. It's got a cracked screen (invisible while in use), a few dead keys, and is running an unsupported OS version. If it makes it through 2021, I'll consider it a miracle. The new models coming along are getting rave reviews, so that should soften the blow.

So this laptop of mine that died is a late 2013 MacBook Pro. Since I bought it brand new, I've replaced the screen on it twice, the motherboard once, the keyboard THREE times, and the power port once. Right now, it's doing this thing where it just shuts off for no reason. When I stuck the motherboard in the oven for 10 minutes at 350 degrees F, it fixed it for a good week... then the problem started again and each time I would reflow the solder I would get days out of it then the problem would return. I ordered a new 16" MBP with 32 gigs of RAM and slightly upgraded video RAM and a 1TB SSD. I've been tracking the shipment from China. It hit northern California a few days ago (I'm in So Cal) and now it's in Tennessee for some reason but it's not supposed to arrive until this Wednesday. Right now, in the meantime, I'm using my 2008 Mac Pro tower with dual Xeon processors and 24 gigs of ram, and with an SSD drive as the boot drive the thing runs amazingly well for its age. I'm stuck using High Sierra and the apps I wanna use many of them won't even run in their latest versions.

I wanted to wait for the new chip upgrade but I simply couldn't because I'm in dire straights without my MBP. BUT, on my current upgrade schedule, I might just be lucky enough to never need Rosetta 2 - LOL!

My Toshiba Satellite 2400 is over 18 years old and still in use running WIN XP.

What do you use it for ... Solitare?

I didn't tell you about my PC clone and Apple Macintosh that are both over 35 years old.

You got a Commodore 64 back in that relic pile of yours? They have managed to find their way into a cult following of sorts ... you can see tons of Youtube videos on restoring the C=64 and one company is selling kits where you can build a new one ... for a modest price of $1k! But it has a nifty clear acrylic body so you can see the electrons flow on the inside. lol

At the atomic level like in semiconductors, ohms law is not a universal law. In fact most of the electrical responses to energy matter interactions in the universe DON'T conform to Ohm's law. Internal and external physical characteristics must remain exactly constant for it to be true. For example, Tungsten doesn’t obey Ohm’s Law.

Can we downgrade a law to a theory? I have a feeling as quantum physics continues to evolve, pretty much every which way we understood the universe is going to be re-defined.

 

All laws in science are theories until proven to be wrong.

 

...
Can we downgrade a law to a theory? I have a feeling as quantum physics continues to evolve, pretty much every which way we understood the universe is going to be re-defined.

Ohms's law is very useful but it's just not universal or a real physical law in the sense of a theory that explains a measurement.

Ohms 'law' not being universal is not related to quantum physics. It's a simplification (of constant and linear physical microscopic characteristics) to a circuit value of classical charged particle drift velocity caused by a electric field. Typically of free electrons in a conductor.

https://www.khanacademy.org/science...e/v/ohm-s-law-derivation-using-drift-velocity

Ohm's law - derivation (using drift velocity)

 

My experience:

#1. A big giant 30 killo-gauss water cooled electromagnet.

#2. Controlling a crane magnet for a model railroad.

#3. Designing a tension controller which we ultimately didn't use. I did not incorporate reverse release., but it should have had it.
measuring tension was not incorporated into the design.

 

My experience:

#1. A big giant 30 killo-gauss water cooled electromagnet.

#2. Controlling a crane magnet for a model railroad.

#3. Designing a tension controller which we ultimately didn't use. I did not incorporate reverse release., but it should have had it.
measuring tension was not incorporated into the design.

A tad scaled up for my purposes ... but it sounds like it was fun project.