Why do we use I for Amps in Ohms equation?

[vulturebetrayer]

Why do we use I for Amps in Ohms equation?

This is one of the hardest parts for me learning Ohms law as I always confuse what the I is for.
I have banged it into my head that I is amps, but I do have dyslexia and that makes it difficult if there is no word to associate with the I.

I have googled this and all I ever find are descriptions of Ohms law but can't find a damn thing on why current is I.

It just bugs the hell out of me.

[rfeecs]

From Wikipedia:
https://en.wikipedia.org/wiki/Electric_current

The conventional symbol for current is I, which originates from the French phrase intensité de courant, meaning current intensity.[3][4] Current intensity is often referred to simply as current.[5] The I symbol was used by André-Marie Ampère, after whom the unit of electric current is named, in formulating the eponymous Ampère's force law, which he discovered in 1820.[6] The notation travelled from France to Great Britain, where it became standard, although at least one journal did not change from using C to I until 1896.[7]

[vulturebetrayer]

From Wikipedia:
https://en.wikipedia.org/wiki/Electric_current

The conventional symbol for current is I, which originates from the French phrase intensité de courant, meaning current intensity.[3][4] Current intensity is often referred to simply as current.[5] The I symbol was used by André-Marie Ampère, after whom the unit of electric current is named, in formulating the eponymous Ampère's force law, which he discovered in 1820.[6] The notation travelled from France to Great Britain, where it became standard, although at least one journal did not change from using C to I until 1896.[7]

thanks, not sure how I missed this in wikipedia

for anyone else:
TLDR: INTENSITY of CURRENT

[JS]

Exactly, I is for the intensity of the current.

Side note: It's not only for ?, is the usual symbol for that variable in all the electric stuff. Usually in uppercase when referring to constant current (DC) and in lowercase for when it is changing. So much than the conventional imaginary number ?(-1) is expressed as j for most engineering and physics applications.

JS

[vulturebetrayer]

Exactly, I is for the intensity of the current.

Side note: It's not only for ?, is the usual symbol for that variable in all the electric stuff. Usually in uppercase when referring to constant current (DC) and in lowercase for when it is changing. So much than the conventional imaginary number ?(-1) is expressed as j for most engineering and physics applications.

JS

Is the symbol supposed to be ? or is it a different symbol that the board DB screwed up?

[vulturebetrayer]

If "I" is annoyingly confusing, by no means should you investigate what the meaning of "positive" (vs. "negative") current is, or anything about "anode", "cathode", "anions", "cations", or CGS vs. MKS vs SI vs. other variants of electrical units....EMF...MMF...left hand rule... Fun stuff.

Strangely I don't have a problem with anode and cathode thanks to blowing up LEDs, and also I understand that current is actually backwards from how we design electronics.  I have a lot to learn, and you guys are super helpful, so I appreciate any tips you have on studying these things.

[rstofer]

If "I" is annoyingly confusing, by no means should you investigate what the meaning of "positive" (vs. "negative") current is, or anything about "anode", "cathode", "anions", "cations", or CGS vs. MKS vs SI vs. other variants of electrical units....EMF...MMF...left hand rule... Fun stuff.

Or my personal favorites: curl and divergence

[bitseeker]

And, of course, volts may appear as V, E, or U.

Hmm, there's power in you and I. (all puns intended)

[Jay_Diddy_B]

Hi,

In addition the reasons stated above, C was already used for:

C = Coulomb (unit of charge)

c = Speed of light in a vacuum

C for Capacitance

Regards,

Jay_Diddy_B

[vulturebetrayer]

  alright guess I'll get back to studying. . .

[tggzzz]

Ah, but wait until you start to consider "small signal" voltages and currents in non-linear components such as diodes and transistors etc. That's represented as "i", not "I".

Wait until you start on the current flow through inductors and capacitors. That's at 90degrees to the voltage and is represented using complex numbers. Now a mathematician represents a complex number as "a+ib", which would be ambiguous where currents are involved - so "j" is used to represent sqrt(-1), as in "a+jb".

[R005T3r]

I use i for the imaginary unit, and yes I write i and I circle it.

Maybe you should consider: s and 5 in the Fourier transforms, especially when you are at exams and you can't distinguish the variable to the bloody 5....

[tggzzz]

I use i for the imaginary unit, and yes I write i and I circle it.

Maybe you should consider: s and 5 in the Fourier transforms, especially when you are at exams and you can't distinguish the variable to the bloody 5....

Don't forget 2 and z. I've copied a maths lecturer, who scribbled furiously - and crossed his z.

[R005T3r]

Lectures at university = recording session.

It's simply impossible to understand everything they say or take notes about whatever they do. The best way is to record everything(HD audio + video) they do and while you take notes you start adding up merkers in both the recordings and the notes. Guaranteed you can easly skip trought the lessions without wasting your time.

Also, if you end up by taking notes in the wrong way, then when you want to study at home 

[tszaboo]

The real fun starts, when you start learning Electro Magnetic Fields (or equivalent) and suddenly ? means five different stuff. I think we used up all the Latin and Greek alphabet twice over the course. Capital meaning different things.
I still cannot write xi properly. Anyone wondering, it means Spatial frequency, Potential difference (AKA u), and something with Taylor.

[tggzzz]

Lectures at university = recording session.

It's simply impossible to understand everything they say or take notes about whatever they do. The best way is to record everything(HD audio + video) they do and while you take notes you start adding up merkers in both the recordings and the notes. Guaranteed you can easly skip trought the lessions without wasting your time.

Rubbish, unless at  a rubbish university.

The techinique I rapidly adopted was to scribble down everything they said/wrote, sort-of understanding it. Then, within half a day (while it was fresh in my mind), to go over my scribbles and re-write them (a) neatly, (b) comprehendably and (c) filling in the bits I thought I understood but then realised I didn't understand. That made the next lecture easier to follow, and made revision much easier.

Sure, that's extra "unnecessary" work. Deal with it.

HD video/audio and most handouts are a trap, because it enables you to avoid (c) above. It is all too easy to convince yourself you understand something - until you try to "teach" yourself by explaining it to yourself.

Also, if you end up by taking notes in the wrong way, then when you want to study at home 

Yes. See above for a good way of taking notes.

[Dave]

If students did all of that after every single day of lectures, who would have time for going out for beers?
Checkmate.

[tggzzz]

If students did all of that after every single day of lectures, who would have time for going out for beers?
Checkmate.

"After" is too late. I did it "during", within a couple of hours.

That leaves adequate beer time!

[Zero999]

Lectures at university = recording session.

It's simply impossible to understand everything they say or take notes about whatever they do. The best way is to record everything(HD audio + video) they do and while you take notes you start adding up merkers in both the recordings and the notes. Guaranteed you can easly skip trought the lessions without wasting your time.

Rubbish, unless at  a rubbish university.

The techinique I rapidly adopted was to scribble down everything they said/wrote, sort-of understanding it. Then, within half a day (while it was fresh in my mind), to go over my scribbles and re-write them (a) neatly, (b) comprehendably and (c) filling in the bits I thought I understood but then realised I didn't understand. That made the next lecture easier to follow, and made revision much easier.

Sure, that's extra "unnecessary" work. Deal with it.

HD video/audio and most handouts are a trap, because it enables you to avoid (c) above. It is all too easy to convince yourself you understand something - until you try to "teach" yourself by explaining it to yourself.

Has it ever occurred to you that different methods suit different people?

I couldn't write fast enough to keep up with the lecturer. I used to take my laptop in any type a lot but that wasn't easy for formulae. I found it easier to focus on understanding it, rather than note taking. If I tried too hard to get everything down on paper, it would just be an illegible mess and I didn't take any of it in, so I might as well had not bothered going. Fortunately, I managed to get copies of the notes from the lecturer and other students.

As long as you work through everything and make sure you fully understand it, it doesn't really matter whether you've physically written it down or not.

Exams were a bit of a bugger but allowed a bit of extra time in exams to write everything down.

What used to mess me up more than z & 2 was lower and upper case v for instantaneous and steady state voltage, even when typing it.

[mrpackethead]

I went to undidversity b4 lAptopz. The used overhead projectors.

[helius]

Now a mathematician represents a complex number as "a+ib", which would be ambiguous where currents are involved - so "j" is used to represent sqrt(-1), as in "a+jb".

That letter was already in use for sqrt(-1), but in a rather different context: Hamilton's quaternions, where there are three different square roots of -1.
\$ i^2 = j^2 = k^2 = ijk = -1 \$

[R005T3r]

Lectures at university = recording session.

It's simply impossible to understand everything they say or take notes about whatever they do. The best way is to record everything(HD audio + video) they do and while you take notes you start adding up merkers in both the recordings and the notes. Guaranteed you can easly skip trought the lessions without wasting your time.

Rubbish, unless at  a rubbish university.

The techinique I rapidly adopted was to scribble down everything they said/wrote, sort-of understanding it. Then, within half a day (while it was fresh in my mind), to go over my scribbles and re-write them (a) neatly, (b) comprehendably and (c) filling in the bits I thought I understood but then realised I didn't understand. That made the next lecture easier to follow, and made revision much easier.

I've already tried trust me, Actually, that was my method when I attended the college.  In my university the mindset is: "who cares if you don't understand, the lecture must go on, and I must finish the day. The exams are made to f+ck you, so I can go in vacation earlier". With the method you said, you can't  keep it up, it's simply impossible to do so: demonstrations are practically impossible to understand at first glance, not to mention that  you will get distracted at some point and you will lose your concentration. At home you have to prepare the exams during the lectures (in some cases actually at the beginning of the lectures).You won't have half a day to spend on refining, rewriting or even understanding all the things. Rewriting neatly the things: It has proven many times to be a failure in so many subjects...

I know that making videos and recording stuff is not the best way to understand everything, but at least you can have a track of the things you have done and if there's a mismatch from your notes you will soon realize what's wrong: I actually do myself the demonstrations(because if you follow the book you end up that 3 monts won't last). I see them as another tool to pass the exams, period. And I need to pass the bloody exams in order to get the degree, in ANY way.

About social life? there's no social life, you have to study, hard and all the way trough, you stop more than 3 times? you will not pass your exam at this session. Also making friendships... All result in quite not durable ones and in some cases they will drop you because of the "competition climate" there is. Not to mention that companies promplty refuses anyone who have a degree that is not out from a prestigious university.

[galvanix]

If "I" is annoyingly confusing, by no means should you investigate what the meaning of "positive" (vs. "negative") current is, or anything about "anode", "cathode", "anions", "cations", or CGS vs. MKS vs SI vs. other variants of electrical units....EMF...MMF...left hand rule... Fun stuff.

Or my personal favorites: curl and divergence

Don't forget about dots or x's because that's gonna change the operator, although it's always a drunk delta! 

[tggzzz]

Lectures at university = recording session.

It's simply impossible to understand everything they say or take notes about whatever they do. The best way is to record everything(HD audio + video) they do and while you take notes you start adding up merkers in both the recordings and the notes. Guaranteed you can easly skip trought the lessions without wasting your time.

Rubbish, unless at  a rubbish university.

The techinique I rapidly adopted was to scribble down everything they said/wrote, sort-of understanding it. Then, within half a day (while it was fresh in my mind), to go over my scribbles and re-write them (a) neatly, (b) comprehendably and (c) filling in the bits I thought I understood but then realised I didn't understand. That made the next lecture easier to follow, and made revision much easier.

Sure, that's extra "unnecessary" work. Deal with it.

HD video/audio and most handouts are a trap, because it enables you to avoid (c) above. It is all too easy to convince yourself you understand something - until you try to "teach" yourself by explaining it to yourself.

Has it ever occurred to you that different methods suit different people?

Strawman observation; I stated what suited me and a potential disadvantages of other techniques. I did not state they were the only techniques.

I couldn't write fast enough to keep up with the lecturer. I used to take my laptop in any type a lot but that wasn't easy for formulae. I found it easier to focus on understanding it, rather than note taking. If I tried too hard to get everything down on paper, it would just be an illegible mess and I didn't take any of it in, so I might as well had not bothered going. Fortunately, I managed to get copies of the notes from the lecturer and other students.

My notes were pretty illegible, and were incomprehensible after a few hours. Hence my reiterating that it would be too late to wait until the evening.

Using a laptop would have been impossible, not only for formulae but also for diagrams and annotations.

As long as you work through everything and make sure you fully understand it, it doesn't really matter whether you've physically written it down or not.

I never trusted myself to remember it in 9 months time; the written notes were an excellent revision aid.

[TimFox]

To be careful, remember that variables such as V (potential), C (capacitance), and c (velocity) are italicized, while units such as V (volts) and C (coulombs) are not italicized.