Coil Definition and 905 Threads

A coiled coil is a structural motif in proteins in which 2–7 alpha-helices are coiled together like the strands of a rope. (Dimers and trimers are the most common types.) Many coiled coil-type proteins are involved in important biological functions, such as the regulation of gene expression — e.g., transcription factors. Notable examples are the oncoproteins c-Fos and c-jun, as well as the muscle protein tropomyosin.

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  1. J

    I Tangential force on a linear solenoid plunger

    Hello, I know how a plunger in a pull solenoid is pulled to the center of the solenoid. What I am wondering is the following. Does the plunger experience a centering force towards the center of the coil? If the plunger is moved slightly off-axis from the center of a circular coil, will the...
  2. J

    Coil resistance increases from 54 ohms to 8k at 220kHz, why?

    edit: The key thing I am after is why the ferrite might be responsible for the increase in resistance I measure on the coil. Hello, i have a coil designed to be 2.2mH and54 ohms. When an MN60 ferrite (T-ish core) is used with it, the inductance rises to 6.1mH as expected, and the resistance...
  3. C

    Bar magnet wrapped in electromagnetic coil

    If I wrap a coil around a bar magnet and shoot current through the coil so that the magnetic field of the electromagnet is at the same polarity of the bar magnet will I have amplified the magnetic field of the bar magnet maintaining the same magnetic shape but bigger/stronger?
  4. M

    How does Lenz's law delay coil field collapse in magnetos?

    Perhaps the title of this post is not quite correct because I could not find a way to abbreviate what I am asking. Picture a magneto circuit, where, an alternator is used to generate an AC flux into a primary coil of a ignition coil by means of a magnetic core (the primary is wrapped around the...
  5. _maxim_

    A Best coil design for homogeneus NMR RF pulse on liquid discs

    Hi there, we have a NMR spectrometer equipped with a standard bore 54mm cryomagnet working at 14.1 T (600 MHz Larmor Frequency) produced by Oxford. I would implement a special probe capable of generating a RF pulse and reading a NMR answer from a sample that is not standard for such...
  6. A

    Why there's a reading on the voltmeter connected to coil Q?

    Homework Statement The current in coil P is constant. An iron rod is inserted into coil P. Coil Q is placed next to P with a voltmeter connected to it. Explain why, during the time that the rod is moving, there is a reading on the voltmeter connected to coil Q Homework Equations emf=-Dphi/dt...
  7. D

    Exploring Induced Current in a Metal Coil

    Homework Statement The figure shows a metal coil labored as A. Heading torwards a region where a uniform static magnet field exists, poiting torwards the ground (hence X). The coil moves with the same constant velocity. As it enter the magnet field the coil will have an induced current in it...
  8. A

    What happens to a coil of wire as current is increased?

    Homework Statement Homework Equations L = (N * F_b) / I (where F_b is the magnetic flux) emf = -L * (dI/dt) The Attempt at a Solution I originally thought that the inductance would decrease since it is inversely proportional to current. But, looking at the equation for emf, that would...
  9. F

    Induced EMF graph of a very small wire moving through a coil

    Homework Statement Homework Equations induced emf = - d(magnetic flux)/dt The Attempt at a Solution [/B] I believe the graph will start initially curving upwards, because it begins to cut more and more flux lines which lead to an increased induced emf. Once it is "fully" within the...
  10. F

    Magnetic train/battery moving inside coil

    Hello, I have seen several videos online where a small AA battery with neodymium magnets attached to its poles manages to move inside a coil of copper. I think I understand how the battery moves. would a large coil be better than a small coil to make the battery move faster since the area of...
  11. K

    Is an induction coil used in a Gaussmeter?

    hi, i am newbie to this forum and physics i should say. i wanted to ask the physics guys whether induction coils are used in gaussmeters? thanks
  12. cluelessGUY

    Electromagnetic Coil 2 SS Rods Converging

    Howdy all, I'm looking at having two (preferably) stainless steel rods inside a plastic tube (for insulation and so they don't touch) with a push spring inside and between the two rods pushing each other away from one another, when not activated inside of an electromagnetic coil. When the coil...
  13. L

    Calculating the EMF in the coil while the field is changing

    Homework Statement A coil with 200 turns of wire is wrapped on an 18.0 cm square frame. Each turn has the same area, equal to that of the frame, and the total resistance of the coil is 2.0Ω . A uniform magnetic field is applied perpendicularly to the plane of the coil. If the field changes...
  14. alfab

    Why does the speed of the magnet matter in a coil?

    I am currently studying Faraday's law and electromagnets and in class we were told that if you had a coil and say a bar magnet was passed through it the faster the magnetic field was applied to the coil the greater the induced voltage or emf would be. I do not understand why the speed would...
  15. Undacuva

    Why Do Generators Use Coils Instead of Pipes?

    Hi, I understand you can induce an electrical current by passing a magnet through a copper pipe. If so, why do generators (and motors for that matter) use coils in stead? Do coils allow a stronger current or greater efficiency? Where can I go to find out the most energy-efficient design for a...
  16. T

    Number of turns vs. wire length affecting voltage in coil

    When winding a coil around a magnetic core, if you wanted to tap the coil such that each half has the same AC voltage output, would you: A) wind each part at the same RPM for the same amount of time, to get the same number of turns for each, or B) wind the second part proportionally less, to...
  17. cluelessGUY

    Magnet clamp repelling in coil

    I have a practical question. I want to make a rubber (silicone) hose/plug that is pinched closed by two magnets ( very strong magnets such as ones from a hard drive the Neodymium kind). I want to place then into a coil and when I want the liquid to flow, I want to turn on the coil and have the...
  18. CricK0es

    Applications of the Helmholtz Coil: Shielding and Stabilizing Fields

    Homework Statement Hi, I've got a presentation on an experiment we did using the Helmholtz coil and I'm starting to run dry on material. As some additional applications I found that you can: - Use the coil set up to cancel external interference (Shield other experiments? Not sure about that...
  19. T

    EM Induction:current in one coil inducing current in another

    Homework Statement Two coils P and Q are placed close to one another, as shown in the first figure attached. The current in coil P is now varied as shown in the second figure. Show the variation with time of the reading of the voltmeter connected to coil Q for time t = 0 to time t = t 2...
  20. Nikhil N

    How to check the condition of coil in the relay?

    I am using the relay as chatter. That is I am continuously on-off the relay to produce bursts. I am using 12V DC relay. I got voltage upto ~120V while it is switching very fast initially. Now I am not getting high voltage while switching. I am getting only ~10V. What may be the reason? Is it...
  21. G

    Autotransformer: Why does primary current go through coil?

    Hi. Why is it that in an autotransformer apparently most of the primary current goes through the winding and not through the load?
  22. Elektrokaninen

    Formula for calculating the output voltage of a pickup coil

    It should be possible to calculate the output voltage in millivolts of a pickup coil at a given frequency, based on the number of turns of wire, the wire resistance / meter, the inductance of the coil in Henrys, coil capacitance, the BH max in Joule, or flux density in Tesla, and volume of the...
  23. S

    What is magnetic force generated by planar spiral coil?

    Hello everybody, I have a planar spiral coil with wire. I want to move a magnet in vertical direction with the magnetic force generated by coil. I want to know how much impulsion to magnet will be occurred on vertical direction. I have been searching for the answer but I am a little bit...
  24. N

    Magnetic flux and how to manipulate it discussion anyone?

    Good day all, I am looking to discuss how to manipulate the magnetic flux of a coil. I unfortunately lack the math skills to calculate what I actually need to build for my project. I have been coop up in my garage trying to physically solve the problem but I am running out of time and money for...
  25. T

    What is strain? Why does DNA coil upon itself?

    I have been reading Lehninger's Principles of Biochemistry to understand DNA supercoiling (pg-930). Supercoiling is the twisting of a DNA upon itself and this happens when the two helically wound strands of DNA are either underwound or overwound. The book says that this act of underwinding or...
  26. G

    Self inductance of a superconductor

    Hi. Superconductors can be made hover above or even below magnets. As far as I know, this can be interpreted as an extreme form of Lenz's law: Eddy currents on the surface of the superconductor create an opposing force that is able to cancel gravity since the currents aren't affected by...
  27. A

    How Efficient Is Split-Return Coil Design for Quenching in Induction Heating?

    I am designing an induction heating rig to heat a strip on the surface of a steel sample with repeated quenching, through holes in the heating surface of the coil (shown in the third image). The rig should heat the sample to around 600C in 20 seconds, and quench to 30C in 20 seconds. Firstly...
  28. Rafa_El

    Tesla Coil Questions Answered - Learn More Here!

    So here i am thinking of Tesla coil. I have read that Tesla coil can sustain itself by getting the right "resonance". And I'm wondering how if 2 Tesla coil separated by a magnet based turbin to power the both of it. I read the theory that Tesla coil can amplify the energy because it was based on...
  29. M

    Cause of metal deterioration in heating element coil

    I put a tumble dryer that had been used only a few times back in operation after a decade being completely out of service. Heating failed shortly after switching on. Checked the heating element and noticed that it is broken at a dozen locations. The spiral is very brittle and breaks easily when...
  30. E

    Ansys Maxwell problem -- band around coil is a difficult geometry?

    Hey Guys, through the past years you helped me a lot. But now i have to ask my first question. I am simulating a solenoid, a very easy one, with a core and a coil. And a translational band (2mm). The only problem is, that i cannot put the band correctly because my solenoid is in a housing, the...
  31. A

    What is the Magnetic Flux through a Loop with Opposite Magnetic Fields?

    Homework Statement Homework Equations Flux = DeltaB * Area The Attempt at a Solution : Since the magnetic fields are going in opposite directions through the loop, I assumed that they would have different signs, so I chose 2.0 T to be positive and 1.0 to be negative, so when calculating the...
  32. davidhowie34

    How to find magnetic field in a square coil next to an RC circuit

    Homework Statement 1. (35 pts) You have a coop job helping to test a capacitor energy storage system. There is a rather large capacitor with capacitance, C = 2.02F. It is charged to a potential V = 602.V with the polarity of the capacitor as shown. The large, solid line on the right of the R–C...
  33. Davide Fabri

    Induction Heating Coil Design: Rectangular vs. Spiral Shape

    Goodmornig everybody, I'm working on the design of a power converter for high frequency induction heating. The induction coil should be a flat spiral (pancake) with a rectangular shape, but my customer would like to design it as shown in the following picture. I think it will not work because...
  34. dumbdumNotSmart

    Induced current of a coil on another coil

    Homework Statement We have two coils of copper wire, drawn below. One has a battery connected to it. The other one has a galvonometer connected. If the coil with the voltage is moved closer as shown in the picture, with considerable velocity, what direction will the current induced on the other...
  35. K

    Inductive charging: Emf induced in two coil loops

    Homework Statement So I'm trying to figure out this problem: The base of our charging station is composed of a coil with N1 turns and area A1 connected to a 120 VAC, 60 Hz source. The device has a smaller coil with N2 turns and area A2, which when attached will fit completely inside the...
  36. moenste

    Calculate the magnetic flux density

    Homework Statement The magnetic flux density in the vicinity of a large air-cored electromagnet is determined by measuring the induced flow of charge in a small coil as the current in the electromagnet is switched on -- see the diagram below. Calculate the magnetic flux density at the...
  37. moenste

    What charge circulates through the coil?

    Homework Statement Describe and account for two constructional differences between a moving-coil galvanometer used to measure current and the ballistic form of the instrument. An electromagnet has plane-parallel pole faces. Give details of an experiment, using search coil and ballistic...
  38. FelixTheWhale

    Magnetic Field of Current loop around the Core

    Hello friends, I am trying to find how calculate the magnetic field created by current loop considering that there is a some geometry of material that can enhance the magnetic field. I thought it can be solved by multipling by permeability μ but realized that the iron core changes the picture of...
  39. N

    Correct formula for induced voltage with a stationary coil?

    I'm making an AC generator with a stationary coil and rotating magnets. What would be the correct formula to find induced voltage at a certain rotation speed (along with the units)? All sources I've found are either non-applicable or do not explain what units to use. Thank you for the help.
  40. Y

    Engineering Finding required coil current (magnetic circuit)

    Homework Statement Toroidal core N = 1000 turns R = 6cm r = 1cm established a total flux of 0.0002 Wb in a non-magnetic core. Find the required coil current
  41. M

    Faraday's and Lenz law - Experiment with AC coil and Cu ring

    Hi, can someone explain me the next experiment: If I have an AC coil on iron stick, and if I put Cu ring on that stick concentric with AC coil, when I turn coil power supply, the ring will levitate on some height. My question is: Powered AC coil produces an AC magnetic field. If I put a...
  42. D

    Solenoid Diagram Homework: Right Hand Rule Explained

    Homework Statement (http://imagemap-generator.dariodomi.de/uploads/160725_010743_e42ea59f2569dfbV.png ) Homework Equations No equations or anything. Just need a visual concept understanding (11U Physics) The Attempt at a Solution The solutions say that all compasses should point east... So...
  43. Harkaran Singh

    Heat Transfer Calculations for Hot Pipe Coil Setup

    Hi guys, I need help with heat transfer calculations The scenario is : Installing a coil around a hot pipe and extract the heat from the hot pipe to heat the fluid flowing through the coil. The whole assembly is insulated. I need methods/formulas to calculate the amount of heat transferred so...
  44. RoboNerd

    Question about strength of magnetic field down coil (solenoid)

    Homework Statement Hi everyone. I was reading through a book and came across the following question and explanation: " You are given two 200 meter strands of identical copper wire. With one strand you create a coil whose radius is 2 cm. With the second strand you create a 4 cm coil. Assuming...
  45. JohnBM

    Low Level EMF and Helmholtz coil design

    The problem statement: I want to produce an LL-EMF of a specific amplitude and frequency in a pair of Helmholtz coils of pre determined radius. The frequency and amplitude are derived from the following equations from this publication...
  46. CopyOfA

    Modeling and Measuring an Electromagnetic Coil in ANSYS HFSS

    I've been attempting to model a simple electromagnetic coil using HFSS, and have so far been unsuccessful. I have no problems constructing the coil; this is a simple geometry problem. I have a wire of a known geometry with insulation surrounding the wire, then a construct a helical path and then...
  47. A

    Position of a coil relative to the magnetic flux

    Does a magnet have to penetrate the plane of a coil in order to generate an emf in the coil? Would an emf be obtained if the coil only passes through the magnetic lines of force, without the magnet crossing the plane of the coil? Thank you.
  48. H

    Magnetism in Coils: Why PD Changes Direction?

    This is a graph for a magnet falling through a coil, it shows the p.d induced in the coil (the induced emf) when the magnet enters and then shows the induced emf in the coil when the magnet leaves. My question is why does the p.d appear to change direction? (i.e why the positive and negative...
  49. P

    Voltage in secondary coil of transformer

    Homework Statement A Primary coil, with ##n_1## turns, is driven with a voltage ##V=V_0sin(wt)## Find the voltage in a secondary coil, with ##n_2## turns, as a function of time Homework EquationsThe Attempt at a Solution Mutual Inductance ##M=\mu_0 n_1 n_2/l *area## ##emf=-d\phi/dt##...
  50. shintashi

    Coil Winding Orientation and Pattern....

    OK, so imagine you have a wire coiling over itself, in a near concentric spiral. When you get to the outer most edge, such as 10 or 100 wrappings depending on thickness, you then bend the wire so it's one diameter of the wire over and then start spiraling inward, till you get to the smallest...
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