thin walled rubber pipe filled with 0.1molar salt water (not flowing) is coiled in shape of a solenoid .
electric current of 4 amps is made to flow through water.
length of solenoid = 50 cm.
no of turns per cm length (along axis)= 10
radius of solenoid = 3 cm
will the solenoid be able to attract iron nails at distance of 10 cm from one end?

 

It will certainly exert a force on the nails, but whether that is big enough to do what you want depends on factors such as what size are the nails, do you want them to move, are they suspended on threads or resting on a surface, are they aligned, ......?
I have to ask: why the water-filled tube rather than a simple wire?

 

You need a core. And it will depend on nail composition and size.

 

On second thought, do you get a magnetic field? In a ionic solution, one should get both positive and negative flow. One might not get a net H field.

 

On second thought, do you get a magnetic field? In a ionic solution, one should get both positive and negative flow. One might not get a net H field.

But as the positive and negative ions move in opposite directions their effects should add not cancel.

 

You need a core.

Agreed. This will dramatically increase the field.

 

AlbertHall.......let's say that the H fields add........which is most likely (because of handedness).....will there be a voltage drop across the coil?

Is it possible for a coil to express a H field without a voltage drop?

 

There will be a voltage drop because salt water is not a perfect conductor - it will have a resistance.

The magnetic field depends on amp•turns. No ∆V term.

 

Won't the polarity of the negative current drop cancel the polarity of the positive voltage drop?

 

Is it possible for a coil to express a H field without a voltage drop?

There will be a voltage drop. Saltwater is conductive but it is not a superconductor.
Even in superconductors (no voltage drop) a current produces a magnetic field.
https://en.wikipedia.org/wiki/Superconductivity
"Superconductors are also able to maintain a current with no applied voltage whatsoever, a property exploited in superconducting electromagnets such as those found in MRI machines."

 

Won't the polarity of the negative current drop cancel the polarity of the positive voltage drop?

The voltage drops are of opposite polarity but in opposite directions and thus add rather than cancel.

 

ok....so does that mean....that if everything being equal (voltage and current and resistance of wire coil and saline coil equal.).......if I change out a wire coil for a saline coil......we get a stronger H field and a larger voltage drop?

 

I would have thought the lack of permeability (of free air) would be so low as to not be useful for this application?
It would be hard enough to achieve the result in the OP with soft iron, IMO.
Incidentally what Walter White and Jessie supposedly did with a lift magnet was totally bogus.
Max.

 

Does a tube of saline have inductance?

 

A metal conductor expresses a magnetic field. We can fold or loop the conductor to add and converge this field.

Does a saline current express a magnetic field?

 

ok....so does that mean....that if everything being equal (voltage and current and resistance of wire coil and saline coil equal.).......if I change out a wire coil for a saline coil......we get a stronger H field and a larger voltage drop?

The magnetic field is only determined by current, number of turns, and physical layout.

 

Ok then. I have never seen one. It would really be interesting. I would think that you would still need a core.

I wonder what circumstance would require such a setup. What would be the advantage?

Is this coil used in the atmosphere?

 

Ok then. I have never seen one.

That's because it's somewhat impractical. The salt water at 0.1M will have a conductivity of only about 10µS/cm. Compare to copper wire at 6x10^5 S/cm. Note S versus µS.

It'll take a high voltage to drive enough current to get much of a field. The high voltage will cause electrolysis, so I'm not sure this has any chance at all.

 

I read on another site that the water must be moving for the field. But it was just comments.

Roger on the current wayneh......we can fix that.....I would like to see if we can get a field from it.

Been looking for some tubing.

 

Could we add salt to water, then use a magnetic field to pump it?