Coil Definition and 864 Threads

How come the magnetic field outside a solenoid is practically zero? I've read reasons along the lines of: -The magnetic field cancels out on the outside. Of course the net force cancels out, but what if you have an object placed on just one spot? The force on that object clearly is not 0...

I had a friend contact me regarding helping him out with lights on his ATV. I don't get to work on powersports vehicles much but occasionally folks contact me when they have electrical issues. Here's a link to a wiring diagram for the vehicle (it's a late 80s TRX250R)...

I need to graph the current energy on a resistor, capacitor and inductor they are all separate it is not a RLC circuit. This is what I know u(t) = sqrt(2)*220*sin(314*t+π/3) R = 10 Ω L = 3 mH C= 3 mF I have already calculated the current for each component, now I need to calculate the energy...

In descriptions of how an electrical transformer works, I've seen it said that the permeable core "conducts a magnetic field" or "allows magnetism to pass through better than it passes through air", but isn't that description misleading? Isn't it really the case that the permeable material's...

In all tutorials I have read on tesla coils, they have said to use a capacitor spark-gap configuration, to create a tank circuit. I want to know exactly what this means, and what is its purpose. I am not going to build a Tesla coil, I am nearly just interested in the science of it.

Homework Statement A 4.0 cm diameter coil (1000 turns) is at rest in the XY plane. The magnetic field in this region of space is given by B=(0.30i + 0.50t2 k) What is the induced EMF in the coil at t=2.0 seconds Homework Equations ε=dΦ/dt Φ=ABcosθ The Attempt at a Solution ε=[/B]d/dt(...

i'm confused with N , it says that is the number of turns per meter , but is the meter the length of the wire or the coil height ?

What is the general cost for building a tesla coil. I already have a PVC pipe and wiring, but I know I need a board, power supply, coil, led lights, capacitors, resistors, and semi-conductors, etc. I know there are some things I am missing and I am on a budget. If there are any other supplies...

Homework Statement In the inductive circuit shown in Figure 2, the switch S1 is closed 0.75s after switch S2 is closed. Calculate the instantaneous current in the coil 1.5s after switch S1 is closed. Homework Equations T=L/R I=V/R The Attempt at a Solution When S2 is closed: T=L/R =2.4/7.2...

Homework Statement I have a rectangular coil with length L and the cross-section's sides has length a and b (b>a). A wire is tightly wrapped around N times. Calculate the magnetic field inside the coil. Homework Equations The problem I have is that in class we were taught how to calculate...

Homework Statement Given a coil with N turns, a radius of r, a resistance of R', and an induced current i'(t) running through the coil, determine the totale energy converted to heat in the coil for t>=0.EDIT: The circuit on figure 4 consists of a resistance R and a capacitor with capacitance...

Homework Statement [/B] Magnetic field values are often determined by using a device known as a search coil. This technique depends on the measurement of the total charge passing through a coil in a time interval during which the magnetic flux linking the windings changes either because of the...

Magnetic field values are often determined by using a device known as a search coil. This technique depends on the measurement of the total charge passing through a coil in a time interval during which the magnetic flux linking the windings changes either because of the motion of the coil or...

Homework Statement A 0.300 m radius, 487 turn coil is rotated one-fourth of a revolution in 4.17 ms, originally having its plane perpendicular to a uniform magnetic field. (This is 60 rev/s.) Find the magnetic field strength needed to induce an average emf of 10,000 V.[/B]Homework Equations E...

Single Electro magnet with split field Single core with separated counter clock wise and clock wise turns My question: I’m not worried about field strength at the moment, I am just trying to make sure that the field will develop in this manner? Note: Please see picture. If you take a ferrous...

Imagine a spring that has its two ends attached to a wall at the same height. The spring will adopt a kind of a ''U'' shape (maybe a parabollic shape would be more precise). Why are the coils near the wall more distant from each others than the coils at the middle of the spring ? I think it is...

Hi Guys, I'm new on the forum so forgive me if this has been posted before. I'm kindly looking for some advise to build a pulse coil set up to spin a 13,00 gauss 1" diametrically magnetized magnet. I was hoping to use 120 volt rectified dc or the highest voltage that has readily available...

Hey guys, I am trying to design an Inductive Square Antenna Coil that will be milled onto my PCB. I am slightly confused when it comes to the matching circuit. To my understanding the matching circuit is there to have the same impedance value of the antenna, correct? So my matching circuit...

I read on a source from a paper from John D. Ramboz that explains: The incremental pitch-advancement of the coil's helical winding sums over its circumferential length to create an undesirable one-turn loop normal to the axis of the coil (the plane of this loop is parallel to the surface of the...

For research purposes, what would be the result of Electrical flow or magnetic strength if an Insulated copper Coil were wound around a pice of copper pipe?

Homework Statement The coil in a loudspeaker has an inductance of L = 56uH (or 5.6 x 10^-5 H). To produce a sound frequency of 20 kHz, the current must oscillate between peak values of +2.2 A and -2.2 A in one half of a period. What average back emf is induced in the coil during this variation...

Hi everybody. I am trying to understand the concept of impedance matching and tuning of RF coil. As far as I understand there are 2 stages: At the first stage I should match the coil to the source (Let's say with L network method) and the second stage is to tune coil to the desirable frequency...

Hi everybody. I am trying to understand the concept of impedance matching and tuning of RF coil. As far as I understand there are 2 stages: At the first stage I should match the coil to the source (Let's say with L network method) and the second stage is to tune coil to the desirable...

The title is explanatory. I know that an iron core yields a stronger electromagnet. What if you have an electromagnet with an extremely tiny air coil relative to its volume? Does the small air coil diameter effect the electromagnet?

Hi all, I've been using a HV step up transformer (10kV-20W on secondary) lately and I'm wanting to look at the HV pulses on an oscilloscope. The coil is isolated from ground. I know connecting a probe directly to it is dangerous and would ruin my scope. I want to use a differential probe but...

Hi, I'm an hobbyist right now I'm into electric engines, simple engines for low voltage and low current applications; I have noticed that there are many variations about how and what an electric engine can do even considering only DC motors, but basically all the engines that I have examined up...

I have a signal generator that is used to generate 12kHz square waves. I want to use my signal generator to drive a transformer primary coil. My coil has 12 ohms resistance, 50mH, and will have 12V applied to it @ 1A. Can I buy a circuit to drive the coil from the signal generator pulse or do I...

Hello, and thanks for looking at my question. For starters, this is NOT a homework question, or a question I will receive any credit for except maybe a "hey, cool". The level of difficulty is roughly a junior-year Electromagnetics class homework quesiton, I suppose? My Question is rather...

Hi, I am thinking of ways to detect when an electrical device is turned on and off without actually touching or modifying the existing circuitry. More specifically, I have a hand held device powered by 2 x 9V batteries and with 2 electrodes connected through leads and plugs to sockets on the...

Hey guys. I just want to know why electrons in a coil always follow the turns instead of jumping from one turn to another. I mean, in many cases the turns are very close to one another. Also, if I'm not mistaken, electrons travel the shortest distances. Thank you!

Homework Statement A coil, made up of 1850 loops, is inserted in an electric circuit and has a resistance of 45,0Ω. The area of each loop is 4,70⋅10^(-4) m^(2). The coil moves from a region where there's no magnetic field, to a region where the magnetic field is present. The normal to the coil...

Homework Statement hey! I saw you've answered this question before... Hi, I would appreciate any help with the following: The coil in a loudspeaker has an inductance of L = 112 microH. To produce a sound of frequency 40kHz, the current must oscillate between peak values of + and - 4.4 A in...

Homework Statement a magnetic circuit with a coil of 500 turns and a core of sheet steel has an air gap of 1mm. the sheet steel has a mean path length Lss = 0.25 m and a cross section that measures 1cm x 1.6 cm. (assume: u air = u0(not) = 4pi x 10^-7 wb/(Am). determine how much coil current is...

Hi, as I am in need of Low- and Highpass filters i would like to simulate my circuit using LT-Spice. I hope that i can get optimal caps and coils values like that. So i simply started to build my pi-network lowpass filter in LT-Spice and got the simulation results (please check the picture in...

Hi guys, I'm a typical nerd that wanted to do an at home science project but don't want to spend lots of money on this coil. I would love to borrow/rent one if someone could help me. Otherwise if someone new a cheap supplier that i could get one off? It looks like either of these pictures :)...

Hello, I'm investigating the relation of the length and number of turns of a search coil of a fluxmeter (measure magnetic flux). I got to an equation B= qR/nA where q is the quantity of charge passed through search coil R is the combined resistance of search coil and fluxmeter n is the number...

I am wrapping a transducer coil and had a question with the winding direction. Let's say that I am wrapping the wire around a bolt in a clockwise direction. After I reach the halfway point of the wire, if I then reversed the direction I am winding to counter-clockwise, what would it do? I am...

Hello. If we assume an ideal transformer, why do we use a.c current in a transformer? I've searched and answers are that we need a changing electric current to produce a change in magnetic flux, using Ampere's law. However, Faraday's law states that a voltage produced a changing magnetic flux...

I found this formula to approximate the inductance of a coil of wire. But what if a solenoid were composed of N separate loops, where each loop of the solenoid is connected to its own battery? That is, what if the solenoid had the same number of loops and the same geometry, except that each loop...

Hello, I am looking at the possibility of turning a pulley using a bimetallic coil embedded inside. How can I calculate the thermal "spring constant" of the coil, as a function of geometry and material properties? Does anyone know of devices with similar actuation mechanisms? thank you.

there is a toroidal coil , a magnet rotates in the middle of the coil , I wonder what happens when first the magnet that rotates is a permanent magnet , second case if the magnet that rotates is a electromagnet supplied with a certain frequency AC current? I wonder what kind of output we see on...

really need help in designing a helical coil HE. i know i must first do an energy balance to find heat rate.but what next?to find the area needed and the number of turns etc

Hey guys been trying this question for a while now and i just can't seem to find any equations which link the two coils to find average EMF and also the final current I2. I am new to electrical so still learning any help is much appreciated, thanks! Two coils, A and B, are wound on the same...

I have a project I'm working on where I need to have a model train be able to have an electromagnet hold its wheels to the track -- so that it can go "upsides down" and resist derailment. I'm making the wheels and the track -- so all options are on the table. If I used a steel track (say...

Here is my misunderstanding , for the example let's ignore resistance losses , say i have a infinite length of coil , and an infinite strip of magnets passing through that coil, each magnet separated by some distance from the next one , the strip of magnets move through the middle of the coil ...

I am making a small solid state tesla coil. I have the secondary coil, toroid and primary coil but am not sure what to do for a control circuit. I was planning on using two 9 volt batteries for power. Would a DC to Pulse Width Modulator work? This is the one I was thinking of -...

Flux linkage in a wire coil is given by BANcos(theta) with B being flux density, N being the number of turns in a coil and A being the cross sectional area of the coil and theta being the angle between the normal to the plane of the coil and the magnetic field. Is anybody able to explain why it...

If I have a contactor that I want to use with two separate control sources, on a site with a single phase power source, is it possible to connect two 120V control signals to the contactor coil, potentially live at the same time and connected to the same source, without causing a short, or...

Homework Statement 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 ´10-2N. http://members.shaw.ca/barry-barclay/Self-Tests/test11/Magnet20.gif Homework Equations F=IBL B=nμI[/B]The Attempt at a Solution...

Hi! I have some simple questions on the formula for torque on a coil in a magnetic field, ie this one: τ = NIA sinθ where I is the current flowing through the coil, A is the area of one loop, N is the number of loops, B is the magnitude of the magnetic field and θ is the angle between the...