Electric field by a current carrying wire

AI Thread Summary
A wire carrying a current does not induce an electric field if there is no net charge, as the number of positive and negative charges are equal. If there is a net charge, then an electric field will be present. A constant current generates a stable magnetic field, but this does not imply the existence of an electric field. The concept of "static current" is unclear, but it is interpreted as synonymous with constant current. Understanding these principles is essential for analyzing the behavior of electric and magnetic fields in current-carrying wires.
jaobyccdee
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Aside from magnetic field, Does a wire carrying current induce also an electric field? If yes, what rule should i use to find its direction?
 
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Does a wire carrying a current have a net electric charge? What do you think?
 
Yes, so negative charges go one way, and positive charges go another direction. Isn't it?
 
jaobyccdee said:
Yes, so negative charges go one way, and positive charges go another direction. Isn't it?

The picture is usually that negative charges (the electrons) go one way and the positive charges (the atoms that have lost an electron) are fixed in a metal. But there's no reason to assume there are more of one than the other. If there is a net charge then you can't compute it from the current. No, there is no electric field that you can figure out from just knowing the current.
 
1. If there are the same number of positive charge and negative charge, then there's no net charge, and thus no electric field?
2. Can i say since a constant current has a magnetic field that doesn't change, so an electric field is not induced?
3. If the number of positive charge and negative charge are not the same, there is a net charge, then is there an electric field?
4. does a static current same as a constant current?

Thanks a lot!
 
jaobyccdee said:
1. If there are the same number of positive charge and negative charge, then there's no net charge, and thus no electric field?
2. Can i say since a constant current has a magnetic field that doesn't change, so an electric field is not induced?
3. If the number of positive charge and negative charge are not the same, there is a net charge, then is there an electric field?
4. does a static current same as a constant current?

Thanks a lot!

1. That's what Gauss' law would say. 2. A constant current creates a constant magnetic field - but that's not why the electric field is zero. 3. If the wire has a net charge, there will be an electric field. 4. I don't know what "static current" means - the only way I can think of the interpret it is "constant current".
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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