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waqarrashid33
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is resistance of a wire increases with wounding it around a cylinder?
If you coil up a wire that has both the current supply and the current return conductors in the same jacket, there is no increase in inductance, because the magnetic field is between the two opposite-current conductors, and very small field outside. This is the same for both straight and coiled power cords. The inductance is minimum when the two conductors are twisted together in the same jacket.ericgrau said:The wire's DC resistance stays the same, but generating the magnetic field created by the coils resists changes in current because it takes energy to change the strength of the magnetic field. So when the current is changing the total impedance (wire resistance + coil impedance) will increase... For AC (alternating current) circuits, audio sound waves, etc. it makes a difference depending on how fast the current is changing.
DaveC426913 said:All other things (such as length of wire and thickness) being equal, winding it around a cylinder will increase resistance. The current running through the wire creates a magnetic field which then reacts to impede the current.
This can be shown quite easily by coiling an industrial extension cord. If you try to operate a 14V drill using a cord that's coiled, you might only get 10 or 12 volts (and the cord will get quite hot).
mabs239 said:I think the resistence will remain same. The more voltage drop and heated chord will be due to increase in the current because power factor will be lower in this case.
sophiecentaur said:But the inductance is more or less Zero - as stated in at least two posts, along with the reason. Also, the capacitance between the two conductors will be no more than, perhaps 1000pF - also negligable.
mabs239 said:Sophiecentaur,
You raised very good point and I missed it altogather in first reading. OP used the word 'wire', so your conccept requieres some stretch.
Dave's observational setup is a good one to show the effect, but I am not sure what shape is the "industrial extension cord". If it has separate wires then the inductive effect could be even doubled.
sophiecentaur said:If you subscribe to what JC Maxwell wrote about then you will realize that two wires wound into a coil and carrying equal and opposite currents generate Zero Magnetic Field. That is to say, there will be no inductance. Don't argue that one with me - argue it with the first textbook you care to pick up!
mabs239 said:afaik, most 'industrial extension cords' consist of three conductors.
If you subscribe to what JC Maxwell wrote about then you will realize that two wires wound into a coil and carrying equal currents generate double Magnetic Field as copared to just one wire.
Your two wires might as well be treated as one wire by winding the second wire in reverse direction.
Now for the other points:
1. I agree but including the points in post4
2. You can't say that. It depends upon the length of the wire, cross-sectional area of the final coil and the materal through which magnetic flux flows. (I see you mentioned two of the three factors)
3. This is a very special case. You do have other ways of winding where reactance is not necessarily zero.
DaveC is referring to the inductance that is created when you wind a wire around a solenoid. The inductance is effectively in series with the resistance, increasing the magnitude of the impedance for an AC signal.Per Oni said:I don’t understand DaveC426913’s post #5.
Redbelly98 said:DaveC is referring to the inductance that is created when you wind a wire around a solenoid. The inductance is effectively in series with the resistance, increasing the magnitude of the impedance for an AC signal.
But the OP specifically said resistance, not impedance, and the wire's resistance would not be changed by the simple act of winding the wire.
This whole discussion could benefit from clarification and involvement by the OP.
I had missed that part of Dave's post (#5) earlier. It has me puzzled, why would a 14V drill, presumably battery-powered and cordless, have a cord attached to it in the first place?Per Oni said:Following on from previous posts the impedance is going to be small. The I think the reason Dave's industrial cord gets a bit hotter is that there's a lot of wire confined to a small space with not much ventilation.
Winding a wire around a cylinder increases its resistance. This is because the wire is stretched and its cross-sectional area is reduced, leading to a higher resistance.
The resistance of a wire increases when wound around a cylinder because the wire is stretched, reducing its cross-sectional area and increasing its resistance. Additionally, the increased length of the wire also contributes to the overall increase in resistance.
Yes, the material of the cylinder can affect the resistance of the wound wire. If the cylinder is made of a conductive material, it can act as an additional pathway for the electric current to flow, reducing the overall resistance. However, if the cylinder is made of a non-conductive material, it will have no effect on the resistance of the wire.
Yes, there is a limit to how much the resistance of a wire can increase when wound around a cylinder. This limit is determined by the physical properties of the wire, such as its length, diameter, and material. Additionally, the number of times the wire is wound around the cylinder can also impact the overall increase in resistance.
The diameter of the cylinder can affect the resistance of the wound wire. A smaller diameter cylinder will lead to a higher increase in resistance, as the wire will be stretched more and have a smaller cross-sectional area. Conversely, a larger diameter cylinder will result in a smaller increase in resistance.