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. I

    EMF induced in coil by magnetic field

    Homework Statement Homework Equations The Attempt at a Solution Well I tried this (I thought it'd work, but it's not the right answer and I'm not sure how to do it now) Anyway this is my attempt: \Phi = \mu_{o}\frac{NIA}{\ell} \\ \varepsilon=N\frac{d\Phi}{dt} So then...
  2. K

    Coil Design: 24V DC 200W | Technical Assistance

    I need a technical assistance in designing of a coil which will work on 24V DC supply with a maximum wattage of 200W suggest me the coil guage, no of turns and the coil ID & OD.
  3. J

    Can Tesla Coils Zap Mosquitoes in Flight?

    Will the high-voltage arc from a tesla coil zap flying insects like mosquitoes if they are close enough to it but are still airborne?
  4. A

    Magnet Through Coil Clarification

    Hey guys. I'm building a mini electric generator and I would like some clarification on Faraday's Law. So his law states that: V=-N*(ΔBA)/(Δt) Where voltage generated equals the number of turns times the negative rate of magnetic flux. So my question regards the number of turns part...
  5. K

    Induced emf in coil with decreasing current

    A single-turn circular loop of radius R = 0.197 m is coaxial with a long 1740 turn solenoid of radius 0.0410 m and length 0.890 m, as seen in the figure below. (picture in URL)...
  6. U

    Ignition coil as Hvdc transformer

    Can a large scale ignition coil drive type circuit can be used for stepping up the dc voltage
  7. N

    Coil, 110 GA, r = 70m. How much tension force is generated?

    Homework Statement I need to generate a field of B = 10 T at the center of a magnetic loop (coil). The coil should have r = 70 m. The coil material itself should be a cable of r = 0.2 m. The question, how much mechanical stress is applied throughout the loop? I'm trying to figure out, if such...
  8. L

    Lorentz force in a toroid coil

    Hi, I'm having a major issue trying to work out where the resultant lorentz force might act when I have a wire coiled around a doughnut (toroid) shape. Am I right in saying that there will be a resultant lorentz force acting to crush the doughnut because there will be a slightly denser...
  9. B

    Magnet Coil Turns and wire calculation

    Hello Friends I am working on home made electromagnet and I have only volt & Ohms details like 12Volt DC, 24Volt DC & 240V AC and ohms is 80Ω, 100Ω & 120Ω for all for example 12VDC 80 ohms coil, 12VDC 100ohms,24VDC 80Ohms coil...etc. now i want to know which copper gauge we have to choose...
  10. T

    Magnetic field from a coil (on Mathematica)

    Hello guys, I'm trying to find the configuration of two circular coils in a configuration similar to Helmholtz coils that would homogenize the magnetic field best at a volume between them. So the first thing step I took in that is use the Biot-Savart law to calculate the magnetic field...
  11. D

    Building an efficient coil gun for photography.

    I have been doing various experiments with my photography and recently built a coil gun. I simply pulled apart a starter-motor solenoid and wrapped the windings around an 8mm tube and fire a short piece of a bolt out of it using a charged 3300uf capacitor and an SCR. None of this is calculated...
  12. N

    Generating 3V-5V with magnetic core coil?

    Hi guys, I'm wondering whether I'd be able to generate around 3V - 5V with a magnetic coil using a high turn ratio in the presence of a changing magnetic field. I know guitar coils can generally produce around 500mV - 1V, I wish to generate around 3V -5V even if it is for a very short time...
  13. U

    A coil of wire is placed along the axis of a solenoid?

    http://img42.imageshack.us/img42/6336/14vu.png please explain your answer! also if u know of similar problems or where this problem is taken from do tell me coz i have an admission exam coming up soon please explain the following: 1. what is the flux like? 3. how the coil spins? z. how is...
  14. W

    Inductance of DC Electromagnet Coil. Help

    I am trying to make a DC electro magnet coil. The Coil is wound up to the core. And works fine. But I'm not being able to find out the inductance of the coil. The Resistance of Coil R20= 490 ohms. Impedence is 523 Ohms. 110v give .21 amps. Please Help.
  15. A

    Shouldn't a wire (coil) just store energy and not give it away?

    Hello, I was thinking about induced currents in a wire(coil). For example when a current from an external source passes through a wire - the changing magnetic field induces a current opposing the current applied (back emf) like a Newton's 3 law and nothing would ever pass through a wire, but the...
  16. R

    I have questions about an electromagnet coil and the winding technique

    Hi guys, I am building an electromagnet to use mainly for its reaching properties. I want to have a large air gap. I don't care if the magnet can only lift a paper clip but I do care if it can move it from a 15 to 20 cm distance or more. I only have 1 core to work with so my choices are only...
  17. O

    Deflection of suspended coil (fluxmeter)

    Homework Statement A fluxmeter is a device sometimes used for measuring magnetic fields. It is a suspended coil instrument in which the suspension has virtually no restoring twist. The instrument is used in series with a search coil which is removed from or rotated in the field to be measured...
  18. S

    Find the mutual inductance between the coil and the wire in two ways

    Homework Statement We have a toroidal coil, and an infinite wire that runs through it on its symmetry axis. (See picture) We need to find the mutual inductance between the coil and the wire in two ways: 1. By running a current through the wire, and finding the induced voltage in the...
  19. T

    Surface Temperature of Helmholtz Coil

    I am designing a Helmholtz Coil with radius 0.5m with 20 gauge Copper wire having 1000 turns. The power generated by passing 1A current through the coil is around 130W. One coil weighs 15.4kg and the cylindrical surface area exposed to air is 0.364m^2. I need to calculate the steady state...
  20. A

    Tutorials for coil design in Maxwell 3D

    Hello people, I am interested in tutorials about coil design for Maxwell 3D. If anyone have good material or knows where to find it, let me know. Regards,
  21. ShreyasR

    Understanding inductance coil.

    I know that an inductor opposes a change in current through it. So in the circuit diagram attachment, When the switch is closed, current starts increasing in the circuit and reaches a maximum value. And When in steady state, if the switch is suddenly turned off, The inductor opposes the sudden...
  22. P

    Electromagnetism, current in coil

    1. A coil of 25 turns of wire is suspended by a thread. When a current flows through the coil, the tension in the thread is reduced by 4.0 x 10-2 N. What are the magnitude and direction of the current? {magnitude of current; direction of current} a) 4.1 A; clockwise b) 0.16 A; clockwise c)...
  23. B

    Kinetic rotational energy of a bar hooked to a coil

    I have solved an exercise and I'd like to know if my proceeding about finding kinetic energy is correct or not, because this is the first time that I "meet" a situation like this. "A bar has mass M and length l. Its extremity A is hooked to a coil (with length at rest l0), its extremity B is...
  24. Femme_physics

    Engineering Transfer function of a circuit with a resistor, capacitor, and coil

    Homework Statement Find the transfer function, Vout(s)/Vin(s) The (s) signifies the laplace plane Homework Equations The Attempt at a Solution I'm keenly aware there is an error here (at least from comparing with the answer sheet). Can you tell me where I went wrong?
  25. H

    Maximizing Winding Area in Coil Design: Benefits and Considerations

    I have been reading about coil design and I have a question. Is there any specific reason a coil design should utilize the entire winding area? I keep reading about this in different literature but none of the literate i have read explains why.
  26. R

    Exploring Magnetic Fields in a Coiled Wire

    Homework Statement A 1.0 m piece of wire is coiled into 200 loops and attached to a voltage source as shown. A. Find the strength of the magnetic field inside the coil if V = 100 V and R = 40 Ω. B. Which direction does the magnetic field point? C. The wire is then uncoiled and re-wrapped so...
  27. V

    Exploring the Magnetic Field of a Bifilar Coil

    I have a doubt bifilar coil makes itself inductance zero... do we get any field around this coil or it also cancels the field around it and makes net field zero..?
  28. W

    If current increases in an coil, what exactly happens?

    Hello! I understand that when current is increased throughout a coil, the magnetic field (B) increases it's strength. I try to compare this with a permanent magnet. The magnetic field in a magnet is due to the electron spins and the force is due to them, when you increase the size of the...
  29. B

    Energy conversion difference in permanent magnet vs. field coil motor

    New here, hello all. My question is more about the field magnet in a running DC motor. First of all, does the current required to maintain a magnetic field change with the load on the motor? And if so, where would this "extra energy" come from in a permanent magnet DC motor?
  30. T

    What Magnetic Field Would be Generated from this Coil Layout (Picture)

    What sort of field would be generated from this type of coil layout?? This isn't homework, just a general inquiry. (see picture)
  31. L

    Why is the EMF Zero in a Uniformly Moving Coil Through a Magnetic Field?

    A flat, rectangular coil of dimensions L and w is pulled with uniform speed v through a uniform magnetic field B with the plane of its area perpendicular to the field (the figure (Figure 1) ).How is the emf zero? My reasons as to why it's zero: the trig part forces the problem to be zero...
  32. D

    Engineering Transfer equation of a Voice coil motor for dissertation

    Homework Statement I'm currently creating a PID control system for a Voice coil motor, my issue is obtaining the transfer equation that relates the voltage to the displacement. Ignoring gravity it is easy however once gravity is included I can't figure out how to rearrange it. Homework...
  33. D

    What Happens When an Uninsulated Wire Coils Around a Metal Object?

    So an insulated electrical wire coiled around metal can create an electromagnet, but what happens if the same wire isn't insulated, and simply makes direct contact with the metal object it is coiled around, does the magnetic field shift then as well? Would there be any other side effects...
  34. S

    (D'arsonval galvanometer) moving coil meter

    Hello, just been reading a little bit about the basics of moving coil meter and one thing is bugging me. First if we have a basic square looped coil in and uniform magnetic field. There is torque ( m x B ) due to the magnetic field and then there is the system/spring attached to the coil...
  35. D

    Having trouble with Helmholtz Coil Experiment Calculations

    Homework Statement Number of wraps of coil on magnetic moment in field: 100 - N_c Number of wraps of coil on Helmholtz coil: 140 - N_h Current through magnetic moment: .796A - I_c Area of magnetic moment: .37m - A_c Radius of Helmholtz coil: .1635m - R_h Current through Helmholtz coil to...
  36. C

    Magnetic field in a solenoid due to induced current in a coil

    Homework Statement A coil of wire with N turns is placed around the a long solenoid with n turns per unit length carrying a current I as shown below, A)If a current I flows through the solenoid, derive an expression for the magnetic flux through the coil and explain why the size and shape...
  37. R

    How is a moving coil meter converted into an ohmmeter?

    Can someone tell me how a moving coil meter is converted into an ohmmeter? I have been searching for relevant derivations for the series type ohmeter but came up with nothing useful. If you have an information source on the subject please share.
  38. M

    Calculate the inductance of a coil of wire

    Homework Statement Calculate the inductance (SI units: Henries) of a coil of wire having a loop diameter of 0.5 cm and coil length of 10 cm. The wire has 1000 loops per meter. Homework Equations I think I can use this equation: L= μₒAN² / x, x = length of wire, μₒ = 4π*10^-7 Tm/A A...
  39. R

    TC-6 Trigger Coil: Can I Increase Voltage Over 190V?

    Hello. My question is relative to practical experience of use of TC-6 trigger coil. In fact I've already used in some rigs TC-36 with 300 V across primary instead of datasheet recommandation which is of 190 V. Now I'm going to use TC-6 (an other 6 kV trigger coil) and I would like to know if...
  40. P

    Making a 10mH Inductor Coil for an LCR Resonant Circuit

    i have to make a 10mH inductor coil for an LCR resonant circuit.could someone please guide me on which gauge of wire to use and how to wind it to make a coil within 5% variation? i need the coil to be close enough to 10 mH for resonance. looking forward to ur help...
  41. M

    Find power of antenna from emf on coil

    I want to find power of the electromagnetic waves generated from a welding cable. I built my own coil antenna that is 6.5 inches in diameter (circular) with 50 turns and hooked up the ends to a digital oscilloscope to measure the voltage (the internal resistance is 1MΩ if it matters). I...
  42. E

    Current in the primary coil of transformers used in rectifier circuits

    Can anyone please clarify if the current in the primary coil of the transformer follows V(s)I(s)=V(p)I(p) when i am trying to figure out the peak, surge and average current through the primary coil of a transformer in a full wave rectifier. Also, if it does, do I just use the peak voltage or...
  43. N

    Calculating the magnetic field inside a field coil

    Homework Statement (This is a bonus question for a lab I have coming up next week.) In this part of the lab, a large field coil is hooked up to a function generator that outputs a 100 kHz, 10V peak-to-peak waveform. A smaller test coil is connected to an oscilloscope and slowly inserted into...
  44. D

    Does mass of top load torus on Tesla coil matter?

    How does the mass of a toroidal top load on a Tesla coil affect performance, assuming all dimensions are similar except for mass? You see, I have one hollow aluminum torus and one torus made of heavy, mostly solid metal. Both same size, but different weights. Thanks!
  45. S

    Electrical Generator and rotating coil

    Homework Statement An electric generator consists of a rectangular coil of wire rotating about its longitudinal axis which is perpendicular to a magnetic field of B = 1.70 × 10-2 T. The coil measures 13.00 cm by 19.00 cm and 200.00 turns of wire. The ends of the wire are connected to an...
  46. U

    Hermholtz Coil differential coefficients

    Homework Statement I'm supposed to show that the first, second and third differential coefficients of the field midway is zero. The B-field at that location is given by: which is field due to a ring x 2.. The Attempt at a Solution I tried to differentiate it with respect to x...
  47. S

    Torque on a coil of wire in a magnetic field.

    Homework Statement A rectangular coil has 120 turns of wire and is of dimensions 10 cm by 15 cm. The coil is placed in a uniform magnetic field B= 2.6 T such that the field lines make an angle of 33 degrees with the direction normal to the coil. Calculate the magnitude of the torque on the...
  48. J

    Magnet through a copper coil - What if poles rotated 90 degress

    I was wondering what voltage or current, if any, would be produced if the basic magnet through a copper coil experiment had the poles rotated 90 degress so north and south faced the top/bottom of the coil rather than the entry/exit points? The attached image has a basic illustration of this...
  49. H

    Calculating Flux density in a DC-DC converter coil

    Hello Everyone. I am working on a DC-DC converter design which uses a transformer with an additional inductive element on the secondary side. The coil charges a large capacitor. Since there is an additional inductive element on the secondary side the inductive element builds up a field...
  50. S

    Max Power from Coil in Magnetic Flux: Turns, Voltage, Current

    Am I understand correct that when an air coil pass through magnetic flux, it create current and emf? power = IV If turns increase, do I get more power? why? If power changes, then how to get out max power.
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