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. O

    Help: Diode doesn't behave as it should when connected to coil

    It's pretty straightforward. I built a circuit to energize a coil and connected a diode in parallel to make sure the discharge won't harm the transistor. The diode is in working order, I've tested it with a multimeter and found that it has a high resistor value when forward-biased and it doesn't...
  2. O

    Energy in an angular (coil) spring system

    Homework Statement A solid disk of mass M and radius R is on a vertical shaft. The shaft is attached to a coil spring which exerts a linear restoring torque of magnitude C\theta, where theta is the angle measured from the static equilibrium position and C is constant. Neglect the mass of the...
  3. O

    Coil with an aliminum cylinder in varying magnetic field

    Hello all, I am trying to apply Faraday's law of induction to calculate emf. I know the cross-sectional area, number of windings, and the magn. flux density (B) as a function of time. So everything looks fine, except one thing. An aliminum cylinder is passing through the coil. In this case...
  4. A

    Calculating Flux in a Coil with Current

    How can we calculate the flux in a coil which carries a current? I am having trouble determining the field at any point inside the coil other than the center? Any help is appreciated...
  5. B

    Can I use 24 Volts input to a car ignition coil?

    I'm feeding the current in pulses via 50v 6800 mfd capacitor. Will it destroy the ignition coil instantly, or will just overheat it? It won't be for automotive use but for general high voltage experiments. As long as instant destruction is a remote possibility, it's easy enough to mitigate...
  6. H

    How do change in magnetic flux induces emf in a coil ?

    According to Faraday's laws... change in magnetic flux linking a coil induces current in the coil.., but for conduction of electrons ...there must be an electric field ! how is the electric field induced in the coil??
  7. A

    Calculating Energy Dissipation in a Rectangular Coil with Time-Varying Current

    Homework Statement A rectangular coil with N = 2,000 turns that has a resistance of 7.90 Ohms is coplanar with a long wire which carries a current which depends on time according to I0 *exp(-t/tau), where I0 = 6.50 A and tau = 4.30 s. The rectangular loop has a width of W = 2.00 cm and length L...
  8. N

    Coil resistence/impedance calculations

    So I've never gotten a straight answer as to how you calculate the resistance of a coil (or cap for that matter). I hesitate to use the term "impedance" because I've been told too many times to count that impedance is the total resistance of a circuit. My professors dance around the topic from...
  9. M

    How is the Induced Magnetic Field Inside a Coil Determined?

    Homework Statement What is the induced magentic field inside the coil? Attached image shows the coil and direction of rotation. Homework Equations Right hand rule of some sort. The Attempt at a Solution Not sure what hand rule to use to find the induced field in the coil. What...
  10. P

    Calculating Magnet Deceleration in a Moving Coil

    Hi! I'm a new face here and have an easy question. I know how to calculate induced current when magnet moves through coil (it's E=BLv) but how do you calculate how much a magnet will decelerate when it goes through the coil? Will it decelarate at all? I have one of those mechanically-powered...
  11. A

    Square coil rotated in a B field

    Homework Statement A 40 turn square coil has an area 11.0 cm2 and is rotated with an angular speed of 110.0 rads in a uniform 1.00 T magnetic field. The axis of the coil is perpendicular to the field at all times. (i.) What is the frequency of the sinusoidal voltage induced across its...
  12. A

    Coil & Resistance: Difference in Magnetic Field/Electronics

    greetings, what is the difference between a wire and a coil with respect to magnetic field or in electronics?
  13. H

    How Do You Design a Coil with a Specific Inductance?

    Hi all, I'm studying computer aided design at university but i have to complete an electronics module. My knowledge is extremely basic and my lecturer 'does not have the time to go through basic physics' so i need a little help. I have been asked to... 'Design a coil which has a given...
  14. G

    Is cross-sectional area of a coil related to it magnetic field strength

    I have to desgin an experiment for physics and and my research question is going to be: How does the cross-sectional area of the solenoid’s coil affect the strength of its magnetic field? This is my hypothesis, my question is if you think the reasoning is valid. I believe I should find it is...
  15. M

    Thick or Thin Wire for Coil Gun: Physics Project

    I am making a coil gun for my physics project and I am wondering if it is better to use a thick wire or a thin wire for the coiling process. (both are magnetic wire) Also, when I coil it, am I supposed to make only one layer of coil as opposed to several layers? Thanks in advance.
  16. H

    Can Series Capacitors Replace a High Voltage Capacitor in a Tesla Coil Setup?

    Is anyone familiar with the Tesla magnatic fueless generator and the associated Tesla coil set up, I have some basic engineering questions before making the coil eg. can three 200V 1uf capacitors in series be used instead of one 600V 1uf capacitor (which is difficult and expensive to purchase)?
  17. D

    Tuning a Coil or Loop Antenna at 49 MHz

    I'm wrestling with the notion that a small coil of wire in a planar flat spiral can be a real tuned antenna. The fact that the coil is only three turns and about the diameter of a quarter further irritates my ability to understand how such a simple thing can be viewed as a real antenna. The...
  18. N

    How Can I Calculate the Power Output of My Electric Coil Design?

    Hi, I'm new here and I apologize up front if my terminology is incorrect. I've been a Civil Engineer for over 30 years, but am very far from an expert in electrical. Sorry if this is an elementary school level question for you guys! I am hoping someone here can either give me a hand or point me...
  19. Z

    What Is the Hamiltonian for a Wire Coil Under Reflection Transformation?

    When applying Noether's theorem to a coil of wire under reflection transformation invariance, what Hamiltonian would one use as as the extermized function? I realize that electromagnetism is not invariant over reflection transformations, that's what I am trying to prove.
  20. L

    Troubleshooting a Coil Gun Project Using a Disposable Camera Circuit

    I'm making a coil gun for a project, and ran into a few problems. I used a circuit from a disposable camera, which had a capacitor and charging circuit. I used two wires attached to the capacitor to connect the circuit to my solenoid. However, after charging the capacitor, nothing seems to...
  21. T

    Problems with tesla coil, looking for suggestions

    I'm not sure if this is the right place to post this, but at this point I'm a little bit desperate, so hopefully I can get some suggestions here... I'm working on a project in which I'm building a Tesla coil. We're using a 15kV transformer, about 15nF capacitance (six 10 nF (16 kV rated)...
  22. S

    How Does a Magnet Affect Compass Direction in a Dual Coil Setup?

    The north pole of a permanent magnet was held over a coil of wire with a hollow core, as shown. A second coil with a hollow core was connected to the first coil as shown. A magnetic compass needle was placed into the second coil, free to rotate in a vertical circle as shown. If the north pole of...
  23. S

    Calculate Electric Field from a Coiled Wire and Loop

    Homework Statement A coil of wire is connected to a power supply, and a current runs in the coil. A single loop of wire is located near the coil, with its axis on the same line as the axis of the coil. The radius of the loop is 3 cm...
  24. G

    Induced magnetic flux through a coil

    Homework Statement A circular conducting coil with N=100 turns and radius "r" is oriented in the xy plane. The leads of the coil are connected to a circuit with resistance "R." A time varying external magnetic flux density "B" is applied along the z-axis. What is the total magnetic flux...
  25. T

    Uncovering the Mysteries of Tesla's Coil for Electromagnets

    Linked below for exact specifications. I haven't heard of this one of Tesla's inventions used for anything, does anyone know if it works, surely it does if it was granted a patent? If so why and what is it used for or if not why not? Anyone? Thanks very much! Link...
  26. B

    Angular speed of rotating coil in the Earth's magnetic field

    Homework Statement A circular loop of wire of radius 1.5 cm is mounted in the Earth’s magnetic field, with no other magnetic fields present. It is free to rotate about an east–west horizontal axis which lies along a diameter of the coil. At what angular speed must it be rotated in order for...
  27. H

    Calculating Distributed Capacitance of a Bifilar Coil?

    Hello everyone, I have been tirelessly searching the net trying to find out how to calculate the distributed capacitance of a multi-layer bifilar coil. Just wondering if anyone here can point me in the right direction?
  28. Y

    Tesla Coil Shocks: Health Effects & Risk

    A friend of mine grabbed a handheld 10,000 volt tesla coil (the metal end) in one hand and a florescent bulb-tube thing in the other, and showed me that he could light the florescent tube using the electricity from the tesla coil. My question is, why did it not shock him, and are there any...
  29. D

    Average Current in Coil Rotated in Magnetic Field

    Homework Statement A circular conducting coil of radius 2.8 cm is placed in a uniform magnetic field of .900 T with the plane of the coil perpendicular to magnetic field. Coil rotated 180 degrees about the axis in .222 seconds. If the coil is made of copper with a diameter of .900 mm, what...
  30. B

    Creating emf with a wire coil and magnet

    Homework Statement We have seen this week that there are 3 ways to generate an emf (voltage or a current) using Faraday's law. Suppose you have a permanent magnet (of your choice), and 5-cm radius coil of wire with 100 loops, and a sledge hammer. Describe the three different ways the loop of...
  31. C

    Exploring the Potential Applications of a Fractal Coil in Electronics

    i came up with a fractal that may have an application in electronics but i don't know what it could be used for. picture a coil wrapped around a coil and so on. picture a small wire half the gauge of a larger wire in which the small wire is wrapped around and the product is coiled around a...
  32. C

    Tesla coil secondary coil wrapped around primary coil

    what would happen if the secondary coil of a tesla coil was wrapped around the primary assuming they were both insulated? and if the secondary wire was half the gauge size of the primary then would the secondary have to be twice as long as the primary for the coil to fit when coiled around the...
  33. M

    Magnetic field produced by coil and solenoid

    Can someone please tell me why the formula for B at the center of a coil and the formula for B inside a solenoid give widely different answers in this problem? From Serway and Vuille, College Physics: "A solenoid with 500 turns, 0.10 m long, carrying a current of 4.0 A and with a radius of...
  34. M

    How fast must a coil be rotating to produce a certain current

    Homework Statement The Attempt at a Solution For letter A, my guess is ξ = dɸB/dt, ɸB = BA (since both magnetic field and the area are constants) After substituting, I ended up with a hanging \frac{d}{dt}.. I'm quite confused. For letter B, I don't know. Will I use the same...
  35. M

    Inductance at the centre of circular coil

    what is the value of e.m.f acting upon charged point particle situated at the centre of a circular coil carrying a changing current
  36. M

    Wind Turbine Science Fair Project - Generator Coil Problem

    Homework Statement My son and I have built a wind turbine following the plans on: Build your own Wind Turbine Designed by Dave Mussell http://www.re-energy.ca/docs/wind-turbine-cp.pdf" . These plans were inspired by the Picoturbine: link to manufacturer and link to PDF. We used 30 AWG...
  37. S

    Can Motor Coil Cross-Section Equations Determine Torque and RPM?

    Are there any coil-cross sections equations?
  38. S

    What is the maximum induced emf in a rotating coil generator?

    Homework Statement In a rotating coil generator, the magnetic field between the poles of an electromagnet has the magnitude .40T. A circular coil between the poles has 120 turns and radius 4.0 cm. The coil rotates with frequency 5Hz. Find the maximum emf induced in the coil. Homework...
  39. J

    Linear Generator Coil Requirements

    Hey I'm interested in designing a linear electricity generator (think magnetic piston moving back and forth in a coil housing) and was wondering if anyone could reference where I should look for designing the coils/magnets. Thanks!
  40. B

    Inductance on equivlent single coil system

    Homework Statement I am attempting to work out the mutual inductance between a pair of single-turn coilds attached to a transmission line. Single-turn coils :inner diameter d, thickness H1 Transmission line: distance between plates d and the parameters L,H2,\delta,\beta and angle \alpha I...
  41. H

    Engineering Ac circuit non inductive resistor and a coil

    Homework Statement A non inductive resistor takes 8A at 100 volts. What inductance of a coil of negligible resistance must be connected in series in order that this load can be supplied from a 220 volt 60 Hz mains. Homework Equations Z^2 = R^2 + XL^2 R=V/I XL = 2pi(frequency)...
  42. V

    Exploring the Electromagnetic Properties of Rodin Coils

    I've been wondering for a while, a Rodin coil's magnetic field generation is the center as a strong open air magnetic field is it unique or is it easily duplicated with different wire configurations that might have this property in a stronger manner more easily. I have tried to find other...
  43. O

    Magnetic Field in a Single Current Coil

    I understand that the magnetic field in a solenoid can be approximated as being constant as the length of the solenoid tends to infinity, but I was wondering if anyone could show me or point me in the direction of a derivation of the precise magnetic field at any point within a single loop of...
  44. P

    Solid State Tesla Coil: Basics & Advice

    Hi everyone, I am have been looking here for a long time, but today is my first day registered. I will be active from now on =). As my first post, I would like to know about the basics and advice about the solid state tesla coil. I would like to do it for my final year project. Is it advisable...
  45. I

    Calculating Coil Turns for 9V Electromotor

    Hey, I am making an electromotor. How many turns of 0.4mm/26 Gauge wire should I make so as to run the motor at 9 Volts? (I`ll count the needed wire length assuming that 1 turn of wire = 8.5cm.) Thank`s in advance & please let me know if you need more info... :smile:
  46. E

    Copper Coil in Table Lamp: Understanding Its Purpose and When to Use an Adapter

    In my table lamp, there is only a switch, and a copper coiled sheets of steel. I am in K9 and would like to know what are those sheets for ? My second very fundamental question is when should we use an adapter ? Thank you
  47. I_am_learning

    Understanding the Tesla Coil: Science & Math Explained in Detail

    Could Someone explain exactly how Tesla coil works with necessary Mathematics and Science. The Wikipedia Article simply states facts but doesn't explain much anything. Well I can't understand this, In the secondary of the 115V/15KV transformer the transformed voltage is 15KV at 50Hz. Then...
  48. N

    Current induced in a coil from inside

    Hi there, If you have a stream of protons passing through the inside of a coil of wire (coils of wire at 45 degrees to current of protons) and say the current of protons induced a certain current in one of the loops, would the current induced in one loop be equal to the current in the entire...
  49. A

    What's the Induced Voltage in a Coil Removed from a Magnetic Field?

    Homework Statement A coil of wire with 100 turns and a cross-sectional area of 0.1 m2 lies with its plane perpendicular to a magnetic field of magnitude 1 T . (a) Describe in your own words the meaning of magnetic flux (b) calculate the total magnetic flux passing through the coil. (c) If the...
  50. S

    Formula for calculating current and or voltage in a coil

    Is there a formula for calculating the voltage and or current in a 2 meter length of coil? The coil being 30mm in diameter with 1mm thick wire coiled around 200 times (for ease of calculation so cable would roughly be 18.8m long) with a resistance of say 16 ohms. Magnet being a cylindrical...
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