# Ohm's Law

Discussion in 'Homework Help' started by gemawannabe, Sep 1, 2006.

1. ### gemawannabe Thread Starter New Member

Sep 1, 2006
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I have been out of school for 25 years and forgot the formula for ohms law. Is it r= a over v? will be taking a test for gema plant and need all the help I can get. Thanks.

2. ### Rail Ranger Member

Aug 22, 2006
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http://members.aol.com/edshomenow/ohm.gif

perhaps this site may be of help, i have lots of saved sites but this answers your immediate question.

Rail

3. ### Dave Retired Moderator

Nov 17, 2003
6,960
144
All you could ever want to know about Ohm's Law

Be sure to check out the rest of the on-line textbook for any information you require.

Dave

Dec 6, 2005
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5. ### EEMajor Well-Known Member

Aug 9, 2006
67
4
Check out http://www.technotetime.com I have one of their watches, and I use it all the time at both school and work. It can be hard to remember everything all the time, and this makes a handy dandy little reference rigth on your wrist.

6. ### Dave Retired Moderator

Nov 17, 2003
6,960
144
Looks pretty good for exams!!

Dave

7. ### Rail Ranger Member

Aug 22, 2006
15
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my question is: are these watches OSHA approved, to wear while on the job, when you're working with electricity, or stand to be shocked being near live electrical work being done?

8. ### Søren Senior Member

Sep 2, 2006
472
28
Hi,

Ohms Law: R = U/I
Watts Law: P = U*I

You might have seen the two triangles:

U
-----
R x I

P
-----
U x I

They don't show up properly here of course and some will want to use E (Electromotive force) instead of U

Cover the one you want to find and the formula is revealed. Mixing the two is simple math.

Those who can't remember those two triangles without strapping trinkets on their wrists needs to go back to school

9. ### Rail Ranger Member

Aug 22, 2006
15
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what's wrong with a little help, especially trying to remember when to use the square root divided by some exponent (facetious of course), jesting aside, after looking at the watches online, i discovered they are a unique timepiece, and they reflect the interest or occupation the wearer boldly displays, but on the serious side of the matter, those of us who work in, around and with electricity know that rings, watches, jewelry are no-no's to be working with. Upon perusal of the site, i did not see the watches being safe to work with while on the job, yet i have a co-worker who wears a completely isolated watch in rubber (or the like) with no metal exposed to the wearer in case of accidental contact with electricity. they do exist, and that said, i was only curious if they were OSHA approved to "one-up" my co-worker, who likes to be the one with the latest in tools, gadgets and the like. the watch is a unique gadget/tool to say the least.

10. ### Søren Senior Member

Sep 2, 2006
472
28
Hi,

Hmm, the word "unique" means "one-of-a-kind", so if you want uniqueness, get it tattooed in a fancy way and while you're at it, get the colour codes as well

Seriously, it's a matter of a little practice to remember the 12 iterations, but if you find those watches etc. fancy, go ahead and buy a bunch

Or, even better... Design your own personal ring, bracelet, necklage or whatever, build it in wax or similar, make a mold and pour it with the metal of your choice, break the mold and it's a truely unique item (however the result will look, but that's up to you )

11. ### Søren Senior Member

Sep 2, 2006
472
28
Hi,

Hmm, the word "unique" means "one-of-a-kind", so if you want uniqueness, get it tattooed in a fancy way and while you're at it, get the colour codes as well

Seriously, it's a matter of a little practice to remember the 12 iterations, but if you find those watches etc. fancy, go ahead and buy a bunch

Or, even better... Design your own personal ring, bracelet, necklage or whatever, build it in wax or similar, make a mold and pour it with the metal of your choice, break the mold and it's a truely unique item (however the result will look, but that's up to you )

12. ### Chris Wright Well-Known Member

Jul 26, 2006
62
0
Soeren, what does the "U" stand for? (E="electromotive force", U=?) and does anybody know why "I" stands for "Current"?

I sympathize with the original author in that I also learned this a long time-a-go, but don't regularly use it and it is easy to forget exactly in what order those three simple little letters go.

I originally learned it as Ohms = Volts/Amps (R=E/I as given today) but after a period of non-use I could never remember if it was the Volts or the Amps that went on top of the division. Now, the Watts = Amps x Volts I could remember, but to make matters worse I was loath to change to the new terms R=E/I and P=IE, until I hit upon the mnemonics EAR and PIE to remember the order.

The form of Ohms' Law E = IR sounds like EAR* and P = IE is, well, PIE

And if you take the first letter and put it on top of the other two, you have the obligatory "triangle" to solve all three forms of each law.

So for the new student or the casual user, just remember EAR and PIE and to stack the first letter for the triangle and you're all set.

*it doesn't even matter if you forget to substitute the "I" for the "A" in EAR if you think of "A" = amps, but you really do need to remember the different terms:

E="electromotive force" meaning Volts
I="current" meaning Amps
R="Resistance" meaning Ohms
P="Power" meaning Watts