Coil Definition and 864 Threads

Hi, I'm currently in a dead spot of my mini-project where I've to decide upon the coil shape. I can't find adequate definition of both coils by the means of: - size - losses - frequency range - inductance - skin depth which makes it impossible to argue which one would be better...

According to many knowledgeable people on the internet, an affordable "high" voltage function generator does not exist. I would have liked to have had electrodes operating at >50v with frequencies up to 15 Mhz but it seems such a function generator is out of my reach. So I want to know if a...

Hello, I recently was thinking about an idea for a perpetual battery. I have an extremely limited amount of Physics knowledge (just a Conceptual Physics [Algebraic Physics] class) as I am still in high school. Does anyone know if this would work: 1. Have a tube 2. Wrap the tube in copper...

1. Homework Statement . A wire coil has both resistance and inductance, and is connected in series to an AC power supply with 80Hz and 180V, drawing 0.4A current and 18W power. The circuit consists of a single loop. 1. Calculate the inductance and resistance of coil 2. Plot vector of...

I have a 13 layer 130mH induction coil that failed and now registers 6.64mH. During the failure analysis the coil was unwound layer by layer and the induction dropped in steps of 0.7-1.5mH to a value of 1.3mH until the 8th layer was removed the the inductance increased to 5.4mH. Then the 9th...

I find it difficult to visualise how the magnetic field generated by a coil can be the same as the field of a permanent magnet. Are the magnetic fields the same or is it just that the effects are the same in that they both attract iron or magnets in the same fashion? Visualising the field...

I want to power a small-ish tesla coil from a 8KV 500W transformer with a voltage doubler to raise that to 16KV. Problem is - it works considerably worse (shorter sparks, LOUD gap) than with a 30KV 100W flyback, spark gap being the same, set at about 12KV. One issue appears to be that...

Homework Statement There are a lot of numbers in this problem. Just about the only way to get it right is to work out each step symbolically first,and then plug numbers into the final symbolic result. Two coils of wire are aligned with their axes along the z-axis,as shown in the...

I'm curious how heat transfers between the heating element in my electric oven and the air in the oven. Say when I first turn on my oven the air is at room temperature (say 70F) and the surface temperature of the heating coil is at say 500F. After some time passes, the air in the oven rises...

Homework Statement This isn't exactly a homework question so there aren't any data/numbers to work with. I just want to know what to do if there are two ferromagnetic cores inside a coil of wire, arranged as concentric cylinders. Or how to account for the air gap between the core and the coil...

This is something that just occurred to me. I was cleaning out an old closet when I came across some speaker wire, kind of like this. I was wondering, what would happen if I wrapped that around a tesla coil secondary coil? You have two separate coils interwinding, essentially, so would the...

I've been doing some test on a rogowski coil that I built. It is like an air-cored current transformer. I am using it to measure high frequency pulses. The picture shows a discharging capacitor being captured by a current probe (above) and by the rogowski coil (below). I don't know what is...

Homework Statement A portion of Nichrome wire of radius 2.50 mm is to be used in winding a heating coil. If the coil must draw a current of 9.25 A when a voltage of 120 V is applied across its ends, find (a) the required resistance of the coil and (b) the length of wire you must use to...

Hi everyone, I encountered a problem as a part of the solution of which I needed to get the i-V relation across a solenoid to gain some intution in the other parts of the problem, which is the well known expression VL=LdiL/dt, where V and i are referenced with respect to the passive sign...

Hello. Say I have a single turn of a coil in an external magnetic field. How do I calculate the voltage induced in this turn ? Initially I would use Faraday's law ∇×E = -j ω B But what should I use for B ? Will B not be a combination of both the external field as well as the field...

Hi there, I'm building a speaker for my intro to EE class. We were given ten small washer magnets, some washers, a nut and a bolt. Enameled wire is also provided. My group prototyped a speaker with the following configuration: Voice coil wrapped around a paper tube which fits around the bolt...

Hello there Its a air core coil I am not too sure how to calculate the number of turns I have to wind. Specs are below Height : 4mm Outside D: 9.5mm Inside D :7mm Coil wire thickness : 40 AWG / 0.08mm Coil resistance : 55 Ohms Coil weight : 0.7g Important figures highlighted. I...

Hi I've built a NST 15kV tesla coil and I hooked it up today and it kinda didn't work. I'm wondering if anyone would like to help me as it's a school project and needs to be finished ASAP so if anyone might have any ideas / advice, that would be amazing! Pictures of all my parts...

Homework Statement A 25-turn coil has a radius of 1 cm and it is carrying a current of 1 A. The coil is in a constant B-field of 1 T (directed along the coil's axis). The coil is moving perpendicularly to the B-field at a speed of 1 m/s. a) Is there an Electromotive force induced in the...

Homework Statement In a model ac generator, a 500 turn rectangular coil, 8.0 cm by 20 cm, rotates at 120 rev/min in a uniform magnetic field of 0.60 T. (a) What is the maximum emf induced in the coil? (b) What is the instantaneous value of the emf in the coil at t = (∏/32)s? Assume that...

Homework Statement There's a diagram in my book but imagine a coil in a square shape attached to a vertical shaft, the diagram for convenience sake represents the coil as one circular wire exactly like a wire actually looks. However, the coil has 410 turns and has an area per turn of 3.1 X...

Actually this not a question, I want to justify whether my concept is right or wrong. So let's start. Faraday's law of electromagnetic induction e=Nd\varphi/dt explains the way of electromagnetic energy conversions. The induced voltage is always ac because the rate of change of flux is...

Homework Statement The following is Problem 1-13 on page 23 from Electrical Engineering Fundamentals, 2nd ed., by Vincent del Toro: "In the configuration shown in Fig. P1-13 the coil has 100 turns and is attached to the rotating member which revolves at 25 \frac{rev}{s}. The magnetic...

Hi. Can someone please explain/tell me what would be the resulting currents trough the coil in every of the three depicted scenarios in the attached picture, I'm confused here. Would the first and the second drawing produce the same result? Is there any current flow in the third drawing. Thanks.

Homework Statement An electric motor has a square coil with 20 turns and an area of 150cm^2. the coil is free to rorate in uniform magnetic field of 300mT. If there is a DC current of 5.00A, passing through the coil: what is the maximum force on one side of the coil? and what is the maximum...

Homework Statement The relationship between the current in an N-turn coil and the flux created by it is given as: \Phi = \frac{ai}{b+ci} Determine the energy stored in the coil when the current varies from 0 to I. Homework Equations W = N \int{i d\Phi} The Attempt at a...

Hi, I have seen a couple of videos on youtube where people simply hook a homemade simple coil of copper wire directly to the House 120v AC. One of them for example hooked a close wound aircore coil with 14 gage wire(01.6mm), 6"(152mm)diameter, about 1" length and 30 turns only.. and...

First, I am not an electrical engineer - I am a hobbyist building a prototype linear-stlye generator based on an idea I had which, for various reasons, cannot be built with magnets that pass completely inside of coil(s) like most of the ones I have seen described for wave energy capture and...

Say I have a coil that is stationary and I have magnets that move past it in a fashion similar to the example in this video: . What is the optimum orientation of the magnet and coil to induce the most current? I know I will want to optimize the rate of change of magnetic flux through the coil as...

Hello, I have cool idea for a device and one hardest part of it is to detect the movement of the object. I think I can use a wire coil, and a small magnet attached to the moving object. When the object passes the wire coil (up or down), there will be small voltage inside the wire coil. It...

I am looking for copper fins the same as would be on a heating pipe. the fins need to be like a coil or slinky. If you have ever used or know who makes them please let me know. I am working on an invention and this is one of the parts i need. 2 to 3" OD and 3/4 to 1" ID

Homework Statement At t=0, a rectangular coil of resistance R = 2 ohms and dimensions w = 3 cm and L = 8 cm enters a region of constant magnetic field B = 1.6 T directed into the screen as shown. The length of the region containing the magnetic field is LB = 15 cm. The coil is observed to...

Hi, So, I am learning about induced emf. I am having a hard time grasping the idea that we are interested in the angle between the normal to the plane of the coil and the magnetic field. In the standard illustration I actually understand it, but the following question confuses me. We are...

I am winding a transformer. I want to get it done right the first time. The transformer has a square core with a coils on opposite legs. I want the polarity to be the same on each coil so how do I wind them? Should the start of the windings be at the top of each coil? Should the...

Homework Statement A solenoid of length 20.0 cm is made of 5000 circular coils. It carries a steady current of 10.0 A. Near its center is places a very flat and small coil with a resistance of 2.50 Ω made of 100 circular loops, each with a radius of 3.00 mm. This small coil is oriented so that...

I attempted to build a tesla coil with a 555 timer but seemed to have failed some where. Perhaps you could take a look and give me some hints on what to try in order to make it work. I attached some pictures as well. I made the secondary coil on a 1/2 (.875 OD) pvc pipe with a 10 to 1 ratio...

Dear Forum, I am attempting to make a treatment mattress or pad for PEMF treatment of osteoporosis. I have osteo, and there are commercial units available, but they cost ~$3K+! I have a capacitor discharge circuit, but need a coil design for the pad. I created a gauss probe with a linear hall...

Homework Statement I'm a summer REU student tasked with building a tri-axial square helmholtz coil setup. My frame will be made of aluminum while the wire used will be copper. I've been researching for days, having actually never studied these coils before, and I'm having serious trouble...

I am studying the vibrations in a coil spring, and want to confirm with others that my derivation is correct. I found that for small oscillations the spring is described by the 1-D wave equation, with wave speed k*l^2/m. where k is the spring constant, l is the spring length, and m is the...

This is for self-study. Homework Statement The armature of a motor has 97 turns each of area 190 cm² and rotates in a uniform magnetic field of 0.33 T. A potential difference of 24 V is applied. If no load is attached and friction is neglected, find the rotational speed at equilibrium...

Homework Statement At a certain place, the Earth's magnetic field has a magnitude B = 59 μT and is inclined downward at an angle of 70º to the horizontal. A flat horizontal circular coil of wire with a radius of 13 cm has 950 turns and a total resistance of 85 Ω. It is connected to a...

Hi Say I have to coils in the anti-Helmholtz configuration as in the attached picture. It is pretty easy to find the field along the z-direction, as this is introduced in introductory EM. However say that I would like to know the field along the x-direction. This I don't know how to find...

I am a mechanical engineer and I'm working on a project in which I need to generate a large magnetic field in a coil of wire. The current system uses AC power (480V or 230V) and I am exploring the possibility of using a DC battery source. The coil is has an OD of 72mm, an ID of 62mm and a...

Homework Statement As shown in the attached figure, two rails of conducting wire,M and N, run parallel to each other on a horizontal plane and are separated by distance l. The rails are in a magnetic field of magnetic flux density B that is in the vertically upward direction. An electrically...

1) Having in mind the Faraday-Lenz law, I'm still not sure if anything happens to it? [1) SOLVED] The area is always the same, the flux idem, flux density as well, so at first glance it would appear nothing happens? This problem was on a exam. 2) Let's say i have a permanent magnet and a...

Good day. Can anyone tell me what the difference is the value of magnetic induction B [T] when using the normal driver coil and the coil of superconductor? Thank you.

Hi all, First of all, sorry if this is a dumb question but I just wanted to make sure. Imagine the body of an electron microscope and the focusing coils on it. I know that due to the generated magnetic fields, the electrons tend to modify its distance to the central axis in a helix-like...

Can somebody explain how it is possible to charge a capacitor using ac voltage? The way I see it is the capacitor wouldn't have time to charge as the voltage is constantly switching. In the case of 60Hz - 120 times a second. I have attached a schematic of a tesla coil which is how I come to...

suppose that i have a wire with a known thickness ... and i want to wind it around a solid cylinder with known dimensions, and in the end make a coil with the same length as the solid cylinder how do i relate between the length of wire required and the diameter of this coil?

Homework Statement A rectangular coil of 80 turns has an area of 0.01m^2. It rotates @ 3000rpm about one of its in plane axes, in a uniform magnetic field having B=1.5T. Calculate the rms voltage generated. Homework Equations 1 Tesla= 1 Weber/m^2. Change in flux of 1 Weber per second...