What is Coil: Definition and 900 Discussions

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. M

    Helmholtz synthesizer experiment

    Hello all! Inspired by the Helmholtz synthesizer, I am experimenting with electromagnetic excitation and tuning forks. http://www.sites.hps.cam.ac.uk/whipple/explore/acoustics/hermanvonhelmholtz/helmholtzssynthesizer/ How can I determine the size and charge of an electromagnet in order to...
  2. Dante Meira

    Magnetic repulsion between a permanent magnet and an air coil

    I would like to receive some input about this "equation" formulated by me, a=f(i), regarding a system with a permanent magnet and an air core coil acting as an electromagnet, as described in the image: I understand that the acceleration provided to the toy car will be a function of the...
  3. PhysicistSarah

    Electrical Optimal Components for a Thomson Coil?

    I'm interested in making a Thompson's Coil after seeing my University's physics II (EM) professor demonstrate Faraday's Law to us using it. It seems like a fun device to demonstrate various principles of Electromagnetism to lay people (Induced Voltage by Faraday's Law, Resistive Heating...
  4. Yousuf Ejazi

    Calculate the induced EMF for angle α

    I have a question in my book and it’s confusing me a bit. I tried to search online for similar solved problems but couldn’t succeed. So here it goes:Calculate the induced EMF in a conductor loop when the angle between \vec{A} ~ and~ \vec{B} ~is~ changed ~from ~{0 °}~ to ~{α °} in 1 second...
  5. S

    Lenz' law: North pole of bar magnet moves away from a coil

    Homework Statement You have a circular coil, and two metal plates a and b. The north pole of a bar magnet is moved away from the coil at a constant velocity(assume the bar magnet and the coil lies along the x axis). On which plate will the excess positive charge appear? Homework EquationsThe...
  6. EF17xx

    AC generator -- Understanding coil voltages as function of position

    Homework Statement In an ac generator Voltage is maximum when the coil is parallel to the direction of magnetic field (B) Voltage is minimum (0) when the coil is perpendicular to the direction of magnetic field (B) I'm trying to understand why. Homework EquationsThe Attempt at a Solution A...
  7. J

    Time constant of an inductor coil

    Homework Statement Homework EquationsThe Attempt at a Solution I think I can solve this problem . But I am bit unsure about how current changes in the circuit and the coil when it is shorted . Before the coil is shorted , there will be no induced EMF across the terminals of the coil ...
  8. Alettix

    Magnetic field in the gap of a tapered torus

    Homework Statement Consider a toroidal electromagnet filled with a magnetic material of large permeability µ. The torus contains a small vacuum gap of length h. Over most of its length the torus has a circular cross section of radius R, but towards the gap the torus is tapered on both of its...
  9. A

    Calculating flux with a magnet and a coil

    Homework Statement [/B] Hey, I'm having some difficulties with my physics project and I hoped someone could help me out. We have to calculate the magnetic field, but first we need to know the flux. This is the setup we got: We have to let a magnet fall through a PVC tube. The tube has a coil...
  10. B

    Stopping a battery from shorting (while driving a magnetic coil)

    Can anyone tell me how to determine the minimum resistance a battery needs to stop it from shorting? for example I'm making an electro magnet, with a 1.5v dc battery cell, but when i turn it on it just drains the battery.
  11. Willow Wanda

    Why do Christmas lights glow green near a Tesla coil?

    Homework Statement For a high school physics class, I chose to build a tesla coil for a real world application assignment. I was able to build it fairly easily and it turned out great. Before presenting to the class next week, I've been seeing its effect on different types of light bulbs and...
  12. I

    Mutual Inductance of Coaxial Tube and Coil

    In my lab we are working with a Coaxial coil and stainless steel tube, and are aiming to find the mutual Inductance. I've done some looking around and have easily found the Inductance of a Coaxial cable, and for that of Coaxial coils, but am having trouble with a combination of the two. The...
  13. F

    Induced voltage in a coil in a three phase permanent magnet axial flux generator

    I am currently designing a three phase permanent magnet axial flux generator, but have a question regarding the voltage induced in the copper coils. Faraday's law defines this voltage as the number of turns in the coil, times the change in flux (external magnetic field times area of coil) over...
  14. K

    Why the voltage on the primary coil changes in an induction stoveplate?

    Translated from Norwegian high-school physics book: I wonder how and why does the voltage change on the primary coil when the cookware is removed or boiled over?
  15. Glenn Emmers

    Can Rogowski Coils Be Used Without an Integrator for HOKA Applications?

    Dear all, I'm currently working on an open core PCB rogowski coil and came up with the following design: I concluded that the asymmetry wouldn't be a problem if the coil is centered precisely around the conductor and cause it's mainly supposed to operate around 50 Hz. Is this a good...
  16. Cardinalmont

    Inducing EMF Through a Coil: Understanding Flux

    Thank you for reading my post. I can understand why a change in magnetic flux through a conducting surface would induce an emf, but how does this work when inducing an emf through a coil? How does the flux through the empty space between the wires have an effect on the electrons in the wire...
  17. davenn

    Tesla Coil Gladiators: Very Cool Fun

    very cool fun
  18. _maxim_

    Moving a solenoid coil in a strong magnetic field

    Hi guys, a solenoid coil 10x4 mm needs to be moved along the vertical axis of a strong magnetic field (up to 14 Tesla) generated by a superconducting magnet. The coil must be contained into a classical probe for NMR spectroscopy, and moved vertically inside that probe. The main issue I am facing...
  19. A

    Mutual inductance of a coil inside a solenoid

    Good day , i have an issue with the derivation of the mutual inductance of coil inside solenoid formula I1 is an alternating current which means that B is varying, and we know that the Flux 21 is equal to the integral of the dot product of B and A2 but as B is varying we CAN NOT take it out...
  20. M

    Full Width Half Maximum of Single Coil

    Homework Statement Determine the Full Width Half Maximum (FWHM) using the single coil equation and fitting parameters. The FWHM is the measure of how broad (wide) a signal is before it loses half of its intensity. In this case, its a measure of the distance spanned before the magnetic field...
  21. C

    Induced EMF in a coil outside a solenoid

    Homework Statement [/B] A conducting coil of radius R is outside a long solenoid with a cross section of radius r. What is the emf induced in the coil? Most example problems of this type I think are solved based on Faraday’s Law. These examples do not use the distance from the solenoid to the...
  22. A

    A Galvanometer of Coil Resistance 50 Ω Deflects Full Scale....

    Homework Statement A galvanometer of coil resistance 50.0 Ω deflects full scale for a current of 3.50 mA. What series resistance should be used with this galvanometer to construct a voltmeter which deflects full scale for 35.0 V Homework Equations /Known Variables[/B] R1 + R2... + Rn = Rtotal...
  23. M

    Design of an Open Coil Spring

    Hi All, I'm trying to design a spring for use in a shock absorber for a college project but my calculations aren't making any sense. I know this is a big ask, but if anyone knows about this stuff I'd appreciate a look. The maximum load is 16.5kN and when it's sitting it will be 5.5kN The...
  24. Aya Elsayed

    The circuit of the induction coil

    When we turn the circuit off . There will be an induced emf through the coil due to the changing magnetic field of the AC . Therefore V=-L . DI/Dt So when the current is zero then the emf has a maximum value . And what about the emf of the source itself ? It's equal to the induced emf? If It...
  25. R

    Magnetic field of solenoid and a coil with multiple turns

    Hi!, I have a question for you geniuses (geniusi?) Why are there two different equations to find the magnetic field of a solenoid and a coil with multiple turns? (According to my textbook) The equations for each are Solenoid: Coil with multiple turns: Why are they different? Is there a...
  26. M

    Find and Buy Antenna Coils for Your Electronics Projects

    please can somebody help, how to find in electronics shop online those components and to buy, is here juse one to make for all, i need juse one, which i can use for all projetcs L1 antenna coil: 470uH with 1 turn wrapped = 2 L2 antenna coil: 470uH...
  27. S

    Would these parts work for a "Tesla Coil" (Slayer Exciter)?

    Hello, I want to make a Slayer Exciter circuit with a Tesla Coil. I have my parts laid out, but I want to make sure that they would work before purchasing them. Off and On switch I have one 0.5'' PVC pipe I assume any would work 9v Battery I own one 9v Battery holder I own one 22k ohms...
  28. patric44

    Discharging argon gas with a homemade tesla coil

    hello guys i made a small crude tesla coil ( slayer exiter ) and i tried it on multiple gas tubes that i had and i have been able to discharge neon , argon but i have a question : how strong the electric field needed to discharge argon gas ?
  29. T

    Current in secondary coil as current in primary increases

    Hi, so the scenario is that the primary coil of a transformer is attached to a battery in a circuit with a variable resistor. The resistor is set to the maximum resistance. As I increase the current in primary coil by reducing resistance at a constant rate, will the current in the secondary...
  30. R

    How to Connect Coils in Series in Ansys Maxwell 3D?

    Hello everyone, wondering if you can give some help with ansys Maxwell 3D modelling. I'm working on the design of a new type of transformer and according my drawings and calculations I need to physical connect (not mutually-inducted) three coils in the secondary side of the transformer, they...
  31. R

    Adding a 2nd Secondary coil & effects

    Hi, We have an induction heater, like a stove top one, not industrial. I want to understand what happens when an additional load is added that it isn't intended to receive. A plate goes on the induction warmer, it gets heated up, then removed and another plate takes it place. What happens if the...
  32. patric44

    Can i cause NMR with a simple slayer exiter (Tesla coil)?

    hello guys i saw a slayer exciter circuit , witch is the crude more simpler version of the tesla coil and i made it , it works quite well but i have some questions. some questions : 1 - how strong is the magnetic field caused by this tesla coil ? it can ionize neon gas , or argon ? 2 - i...
  33. L

    Magnetic Flux through conductor coil

    Homework Statement Consider a conductor loop which rotates about the y-axis with angular velocity w. The positive y-axis is directed into the paper, the x-axis to the right and the z-axis upwards. There is an inhomogeneous magnetic field along the positive x-axis. Calculate the magnetic flux...
  34. peroAlex

    Electromagnet with two cardboard pieces

    Hello! Recently I was going through some old exams and upon encountering this problem (which seemed pretty easy) I got stuck. Exams at my university are composed of individual tasks, each having three subquestions with four plausible answers respectively. Solution sheet gives results only, so...
  35. marcophys

    What's the purpose of this dual coil?

    What's the purpose of this dual coil? It has a blue and red cable. It stood alone, mounted (isolated) on the chassis of a PC PSU. It's in good condition, so I'm keeping it, but what can be achieved with it?
  36. Y

    What force does the current carrying coil feel?

    Homework Statement What direction does the force that the current carrying coil feel point to when a magnetic field is turned on? A magnetic field is turned on and points from bottom to top and passes through a current carrying coil that has current passing through it CCW. Here is a diagram...
  37. D

    How many turns to produce power on a spinning coil

    Does anyone have formulae to calculate the number of turns required on a coil to produce 10V at approx 5W. I wish to have a coil spinning on a 16" diameter former in a 0.25 gauss magnetic field at a minimum of 2.2Hz. I need to be able to work out the size of coil and number of turns to produce...
  38. P

    Help with 3axis Helmholtz Coil

    First of all, hello to all of you. My question is, I want to simulate 3-axis Helholtz Coil in Maxwell 3d. I made some models of it, but I am not sure I got all right - especially ration of coils in x-y-z and their current excitation. Second, i'd like to see H field, or B field plot if some of...
  39. J

    What happens if you use Tesla coil to charge a capacitor?

    I am trying to create a high DC voltage output(with extremely low current output). I thought of something like this. The left coil would be the tesla coil. Can I use this to charge the capacitor and create high DC voltage? What would happen if capacitance was really high?
  40. eigenmax

    Is the output of my ignition coil AC?

    Hello, I am working on a project that requires both high voltage AC and DC. I was going to use an ignition coil for the AC because I thought it's output would be AC, but when I saw this illustration...
  41. E

    The Peculiar Behavior of a large electromagnetic coil

    I have these two very large (ferrous core) coils, They are basically identical, each 200mm long and have a diameter of 100mm. The core is medium grade steel One coil is receiving an input of 8V(peak-to-peak) @ 4 MHz from the function generator. The second coil is placed 1m away, and is...
  42. Asmaa Mohammad

    The average EMF in a coil rotating in a magnetic field

    Homework Statement [/B] Homework EquationsThe Attempt at a Solution Solution for Q1: Solution for Q2: Solution for Q3: Are they correct?
  43. Asmaa Mohammad

    The rate of change in the magnetic field linkage in a coil

    Hi, I would appreciate it if someone explains the difference between these two phases regarding a coil rotates in a uniform magnetic field. 1. The rate with which the coil intercepts the lines of magnetic field in the dynamo is maximum when the plane of the coil is parallel to the lines of the...
  44. T

    One coil twisted in a figure 8 vs. two coils side-by-side

    The side by side coils are round or oval, and wired together in series. Let's say the side by side coils are wound opposite (one clockwise and one counterclockwise) to match the direction of travel of the twisted coil's loops. Each of the side by side coils has the same number of turns as the...
  45. B

    Magnet Coils & EMF Homework Help

    Homework Statement Homework EquationsThe Attempt at a Solution I got a Magnetic field by "Magnetized needle". I think it's just magnet. But i don't know how to get a magnetic flux due to the variable "d" that should be erased.
  46. 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...
  47. 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...
  48. 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?
  49. 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...
  50. _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...
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