Self induction in a straight wire

1. Sep 16, 2010

jpo

Direct current I in a straight wire is decreasing with time. Let's assume dI/dt is large. Will such change produce self-induced current in the direction of I?

If Lenz's law is an equivalent of Newton's 3rd law, how come changes in straight wire meet no resistance?

2. Sep 17, 2010

jpo

It seems to me that the system has to react against the change. Is this true?

3. Sep 17, 2010

ctech4285

i think that is where inductivity comes from or the resistance of change of current. and you need a large field to push the current throw the wire.

4. Sep 17, 2010

jpo

My question is will there be such inductance. I mean, there is no loop and no flux through it

5. Sep 17, 2010

ctech4285

yes. you don't need a loop. a strait wire will do the trick.

6. Sep 17, 2010

thehacker3

any change in current through any object, whether it be a coil or a straight wire, will produce a magnetic field (inductance). The relationship of inductance to the change in current is calculated by lenz's law

7. Sep 17, 2010

jpo

Current decreases with time. Self induction has to presumably supply extra Amps to resist the change. Where will the energy com from to do all this?

8. Sep 17, 2010

mrspeedybob

The magnetic field stores energy. This energy was put there as the current ramped up.

9. Sep 19, 2010

jpo

mrspeedybob,
this seems very reasonable, thank you!