# Can an electromagnetic field be created in a non-metallic coil?

OK, so here's a simple one. When current flows through a wire, it produces a tiny magnetic field. If you bend the wire into a spiral, the fields of each loop merge together forming a field you can actually measure.

But does the conductor have to be metal, or would any conductive material work? E.g., would a plastic tube full of water still produce the same magnetic field? [Assuming the water has enough impurities to be considered a "conductor" to start with, which it usually does.]

Edit for Clarification: OP is talking about a simple electromagnetic coil, without regard to core material or application. Assuming Air Core, would a coil of water in pvc tubing, electrified, produce a measurable magnetic field?

• Theoretically, yes, but the energy needed in such an poor conductor would make it impractical in size/performance. – Passerby Jan 25 '15 at 16:04
• Are you trying to make an electromagnet or a solenoid? – horta Jan 25 '15 at 16:28
• @horta What's the difference? – MathematicalOrchid Jan 25 '15 at 17:16
• An electromagnet uses a core material that's usually ferromagnetic to increase the field strength of the coil. A solenoid is nothing more than a coil generating an electric field. Often solenoid's have an actuator in them that is magnetic and the actuator is then moved by the solenoid. – horta Jan 25 '15 at 17:24
• @Passerby I'm wondering why you've used "an" before "poor" instead of writing "a poor". Is it a typo? – Gurpreet Jan 25 '15 at 17:24

Since the flow of charge through anything constitutes current, and since current creates a magnetic field, the short answer to your question: "Can an electromagnetic field be created in a non-metallic coil?" is "Yes".

Yes, you can make a solenoid without a metal wire. The best conductors aren't metal at all, they're ceramics (i.e. superconductors). Water with impurities will work fine as a solenoid.

If you decide to use an actuator, you'll obviously have to have that have some kind of ferromagnetism or conductivity in the actuator to be capable of induced currents, but this still doesn't require any sort of metal or magnetism on the solenoid coil.

For the sake of ambiguity:

If by solenoid the intent is just a coil & such a coil is to carry current & thus generate a magnetic field.

Yes. Water can easily conduct electricity & with this electrical current flowing around the coil will produce an magnetic field. How good compared to a coil made out of wire? not that good Why? the radius of the coil. The radius influences the inductance and the length & turns influences magnetic strength

B=μI*n/l

L=μr²n²π/l

Could you make the insulation of a waterpipe the same as the enamel insulation on a metallic conductor?

If it is todo with a solenoid associated with linear movement:

Any conductor will do. The key here is the permeability of the material.

http://en.wikipedia.org/wiki/Permeability_%28electromagnetism%29#Values_for_some_common_materials

Compare Iron ( 2.5×10−1 ) to water ( 1.256627×10−6 ) and more importantly to Air (1.25663753×10−6) as it would be an air-cored Solenoid

That is a factor of 20,000

• So... it would still make a magnet, just a really feeble one? – MathematicalOrchid Jan 25 '15 at 16:08
• It would facilitate making an electromagnet BUT it probably won't even be able to exert enough force to counteract its own weight in water. By probably I mean more than likely, I just would rather not go through the maths to prove it – JonRB Jan 25 '15 at 16:10
• a silly amount of current which would cause the water to boil & would probably just about manage to move a grain of sand . – JonRB Jan 25 '15 at 16:12
• exact same link: In engineering, the term may also refer to a variety of transducer devices that convert energy into linear motion. OP intention is unclear – JonRB Jan 25 '15 at 16:42
• I'm glad that you've made a provision in your answer, but you're still putting in a bias against a solenoid made of water. If you have a coil made of ionized water or a coil made of metal with the same properties, you'll have the same solenoid. Whether the OP can make that water solenoid practical is up to him. The OP just wants to understand concepts from the basic nature of the question, and you're throwing him/her curve balls. – horta Jan 25 '15 at 17:06

For a simple solenoid, yes, it has to me metal. Further, it has to be a ferrous metal.

A solenoid works by simple magnetism. Energise a coil to attract a ferrous material.

There are other systems though, called Linear Motors which at first glance look like a solenoid, but in fact work on a completely different principle. These use a powerful magnetic field to induce a current into a conductive non-ferrous material (commonly aluminium) which then in turn generates its own opposing magnetic field. These two fields repel each other and the non-ferrous material moves. It's how "Maglev" trains work.

• But aren't solenoids usually made of copper - which isn't magnetic at all? – MathematicalOrchid Jan 25 '15 at 16:12
• I think you're misunderstanding the OP's question. He's just talking about a coil. I don't see any indication that he's talking about an armature within a coil. The coil doesn't need to be magnetic or a metal at all. – horta Jan 25 '15 at 16:13
• @horta the problem is that solenoid has multiple similar meanings. – Passerby Jan 25 '15 at 18:24

Yes it would, but depending on the medium you'd run into some serious implementation obstacles. In case of water:

• Once a DC current flows through water, it begins to split into hydrogen and oxygen.
• You somehow have to prevent evaporation