# Is in the one-way current have selfinduction? and if yes why, if no why?

## is in the one-way current have selfinduction?

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1. May 6, 2007

2. May 6, 2007

### ZapperZ

Staff Emeritus
If you wish someone to put some EFFORT in answer your question, you should at least put in the same amount of effort in present a clear and unambiguous question. This will not cut it. The geometry of the current make a heck of a difference here. The self-inductance of a straight line current will be different than a coil. Your question gives no such clarification.

Zz.

3. May 6, 2007

### scientist91

But isn't it that the electrons which are going accross conductor have magnetic field, so they are moving and the magnetic field is moving so there is some electromagnetic induction? Logically.

4. May 6, 2007

### lalbatros

Please, before discussing anything, start by translating this sentense:

in an intelligible language.

5. May 6, 2007

### scientist91

If u are from Mars u will not understand for sure.

6. May 6, 2007

### lpfr

I must be martian.

7. May 6, 2007

### jambaugh

I think the best way to express this problem unambiguously is to imagine two widely separated oppositely charged spheres connected through a switch by a straight wire. Then the question is:
When the switch is thrown will the spheres once discharged, recharge somewhat with opposite polarity due to the self induction of the current through the wire. In short is this an LC circuit.

The answer I am certain is: Yes. My well trained intuition tells me this must be the case else electromagnetic waves could not propagate. Even the virtual Maxwell current due to a changing E field must have a component of "self induction" in order for the E-M wave to propagate. However there is a slight chance I am wrong. So do the math or better yet do the physical experiment.

Further I think the calculation of the self inductance per unit length will be the same as if you take the limit on a square loop of wire as the size goes to infinity.

Also try working out the self-inductance per unit length of a coaxial cable as the radius goes to infinity.

Regards,
James Baugh

8. May 6, 2007

### scientist91

Can u explain simpler please. Thank u.

9. May 6, 2007

### Xezlec

If you are asking whether a wire, by itself, has any self-inductance, then yes.

If you are asking whether a constant current flowing in that wire is at all affected by that self-inductance, then no, because inductance doesn't "do" anything unless you have time-varying voltages/currents.

If you are asking anything else, I'm afraid you'll need to spend a little more time working out the English grammar of your sentences. We can't really understand you. Sorry!

10. May 6, 2007

### lpfr

Hard to make simpler than this. If u are from Mars u will not understand for sure.

I totally agree with jambaugh.
The self-inductance per unit length in a coaxial cable is:
$${L\over\ell}={\mu\over2\pi}\ln{R_2\over R_1}$$
R1 and R2 are the radius of the internal and external conductor. When the external radius goes to infinity, self-inductance per unit length tends also to infinity.

11. May 6, 2007

### scientist91

is in the direct current have selfinduction (electromagnet induction)? and if yes why, if no why? Anybody from here have studied physics?

12. May 6, 2007

### Xezlec

OK, I'm pretty sure I already answered your question. Is there some part of my response you are having trouble understanding?

Also, it's irritating that you keep asking the question exactly the same way, after you've been told that your English is completely incomprehensible. Please rephrase if you are not satisfied with any of these answers.

Last edited: May 6, 2007
13. May 6, 2007

### scientist91

What you can't understand in the question? btw- I didn't understand nothing.

14. May 6, 2007

### Office_Shredder

Staff Emeritus
The problem is that your sentence makes no grammatical sense.

For example, if you said "Is there self-inductance by a direct current in a cable?", that would be much clearer. It appears to be approximately what you're asking, but since that question was already answered, you must not mean that.

15. May 6, 2007

### lpfr

Yes. Longtime and better than you.

We have also learned from our parents to be polite.

16. May 6, 2007

### lalbatros

English is not my mother tongue.
But I am quigte sure that this sentense:
- is gramatically incorrect
- cannot be understood, even approximately, by a majority of people
- could not describe a real question in physics, even if corrected for its poor grammar​
If physicsits are martians, then I am one for sure, I have a complete pedigree in physics and engineering as well.

I like precision.

17. May 6, 2007

### scientist91

what is incorrect?
self-induction?
ANSWER ON MY QUESTION IF U KNOW THE ANSWER, DON't TRY TO IMPROVE MY ENGLISH THERE IS ANOTHER TOPIC FOR THAT. SO BE POLITE PLEASE, IF U WANT THE SAME FROM ME>

18. May 6, 2007

### lalbatros

The problem with this sentense is that there are two verbs.

If you were polite, you would at least try to understand why nobody answers your question and you would not assume people here are not physicists, which is really laughable.

All you gave in return is insults.
You are not a gentlemen, nor a physicist.
Or show us if you are.

Last edited: May 6, 2007
19. May 6, 2007

### lpfr

I support totally lalbatros.
I think that a moderator should close this thread.

20. May 6, 2007