Coil Definition and 906 Threads

It is just for teaching experience sharing. Consider a uniform disk. A stretchless and massless wire has been wound on the disk. The end of the wire is attached to the ceiling. Initially the system is at rest as it is shown at the picture. Then the disk is released. It falls down and rotates and...

I don't really know but if I were to guess it would be based on how many turns are in the coil, the diameter of the coil and the flux of the magnet. Unfortunately I couldn't find a formula anywhere.

In the given question they have not provided the dimensions of the coil so I assumed it to be very close to the wire and having negligible dimensions compared to the wire . Then EMF induced in the coil due to the current in the wire comes out as M*a . Which when divided by resistance gives...

Hi. I am reading a textbook about simple DC generator. The situation is if we are rotating a single armature coil within a constant field B, the induced emf will be (if we are to only think about the magnitude), emf= B*l*W*omegaB = magnetic field l = length of the coil W = width of the coil...

I require a small conical spring to open from its compressed pancake height of its wire diameter to a free length of 11mm > 0.2 seconds (20 milliseconds) The large end outer diameter = 7.80mm. The small end inner diameter must be greater than or equal to 2.75mm. The conical's spring's will be...

a. No, because only permanent magnets are suitable to be used as a compass. b. Yes, but only if the coil doesn't have an iron core. c. Yes, but only if the coil can turn easily. I choose (c) , Is that correct ?

So this was a section taken out from a question which I am trying to do shown below I have drawn a sketch to help me visualise of what is going on I have used Fleming's left hand rule to help me determine what direction the force is facing on each side of the coil. For the last part in...

The magnet being used % magnet dimensions [m] d = .0127; r = .00238; %mass of magnet [kg] m_w = .0017; % other constants u_0 = 1.26E-6; % permeability of free space constant T m/A g = 9.81; % gravitational constant in/s^2 %coil properties [22 gauge wire] [m] a = .00635; %radius w =...

These are images from the book Introduction to Electrodynamics by David J. Griffiths . . . My problem is that I'm unable to understand how the current has zero ##\phi## component (I have underlined it in the first image)? I do understand cylindrical coordinates, I know...

Suppose I have a finite sized cylindrical bar magnet of radius $a$ and length $b$. It is coaxial with the $x$ axis and moving from $-\infty$ to $\infty.$ A circular closed wire of radius $r>a$ is in the $y-z$ plane with center at the origin. When the bar center of the bar magnet passes through...

Hello So here is my question Not so sure how to approach this question This is what I have worked out so far which is the magnetic field strength of the solenoid, not sure if this comes in helpful though Thanks for any help!

I recently posted about an air cored electromagnet I was designing. It currently uses 300' of 17 AWG magnet wire, coiled around a .5'' diameter tube. I purchased a DC to DC step up to test different voltages and currents. I noticed while using it that regardless of what current I supplied...

Hi all, I'm trying to understand basics of radiofrequency (RF) coil development for magnetic resonance imaging (MRI). For example, the problem is to develop simple surface single-loop RF coil tuned to 100 MHz. In program Coil32, I set the following parameters: diameter of the loop D = 20 mm...

Homework Statement: Figure shows two mutually coupled coils, for which L11= L22 = 3 + 2/3x (mH) L12 = L21 = 1/3x (mH) where x is in meters, (a) If i1 = 5 A dc and i2 = 0, what is the mutual electrical force between the coils at x = 0.01 m? ( b ) If i1 = 5 A dc and the second coil is...

i tried to build an induction coil. the input voltage is 12.1 volts. the output voltage is 16.5 millivolts maximum. so the voltage in the primary coil is 12.1 volts. the voltage in the secondary coil is 16.5 millivolts maximum. the induction coil consist of a nail. thicker coils form the...

I've recently had a discussion with fellow technicians in the automotive industry about spark plugs and some systems having "opposite polarity" on the ignition coils. (specifically the secondary coil which sends the high voltage pulse to the plug which sparks the fuel) Common sense tells me...

Summary: In a heating by induction experiment performed, the idea was to determine the efficiency of heating up a small steel cylinder, an aluminum cylinder and then compare the two efficiencies. The cylinder was surrounded by a metall coil that alternating current was going through...

I'm already stuck on A. I'm hoping once I figure that out the rest will just fall into place but be prepared for this to take awhile. I understand how to use Faraday's law to get the current or voltage of the system based off the movement of the bar but I have no Idea how to relate the rate of...

My reasoning: Initial Q factor Q1= X1/R After doubling the frequency, reactance also doubles. So, Q2= 2(X1)/R. Hence, Q factor doubles (option a is out). Now, since it is mentioned that the coil has high Q factor, I assumed X >> R and hence, total impedance is approximately equal to the...

We first determine the Laplace force for each value ##\alpha##. $$F_{\alpha} = 5(0.3)(0.4)\sin(\alpha) = 0.6\sin(\alpha) \ \text{N}$$ We then calculate the torque at angle ##\alpha##. $$\tau_{\alpha} = \frac{a}{2} F_{\alpha} = 2.5 F_{\alpha} \ \text{N.m}$$ Then we just plug in ##\alpha## and...

Hi guys, I'm new here. I have been analyzing the behavior of cast iron melts in induction furnaces and realized that at the end of the melt the current increases slightly. The power remains the same. Physically, does anyone know the reason? I imagine to be related to the magnetic permeability...

Summary: FRB's source as Rail and/or Coil Guns (or mass drivers) Hello, I've been studying rail and coil guns recently, and certain applications of this technology can result in some pretty high speeds with a significant amount of mass. I've been wondering if these FRB's could be a result of...

So I just connected a zinkplate and a copperplate in series with a battery 9v and a coil(with a an iron core). All the parts are from a set bought for learning about electricity. Since I was a kid I have many time put the + and the - of a 9V battery on my tongue, and felt the electricity. So...

Hi friends, I am studying this circuit which is the first all electronic television receiver created by Dr. Farnsworth back in 1927. Triode are being employed along with some caps and coils. The design is very simple and clear, basically this receiver is a detector circuit which detects the...

Summary: Mathematical and Physical queries in regards to Electromagnetic Fields and their manipulation of Space-Time. I recently started looking into Einstein's Field Equations, to get a better understanding of how mass distorts and curves the plane of Space-Time, however from doing this I...

So, as it says in the title, I am trying to calculate overall voltage induced in a coreless coil in the cases of it being stationary and moving in an alternating magnetic field. To go more into detail, I would like to create a mathematical model of a coil in an alternating magnetic field that...

I have stated here before I run a points distributor in my 200 Ford six but usually with a Pertronix conversion. After finding a later 200 head (1973) I plan to have it machined for a direct fit 2-barrel carb. Now I am using a 2-barrel adaptor and I want as much spark as possible at the plugs...

A Tesla coil is an electrical resonant transformer circuit designed by inventor Nikola Tesla in 1891. It is used to produce high-voltage, low-current high frequency alternating-current electricity. Tesla tried to transfer energy with a wireless way. It was really difficult...

Hello. So I have a coil and a resistor in parallel connection. It is powered by alternating current. I have to calculate angle between voltage and current, what is the formula? I know the reactive resistance in coil, I know resistance of resistor, voltage across both of them and amps flowing...

I don't understand why a force would be acting on this rectangular coil at all. The magnetic field of the wire would only induce a force on the coil, if the coil had a current flowing through it. At first I would think that the electric field from the varying magnetic field would induce such...

Where should I start?

I will first calculate the magnetic flux of the coil in motion. $$\frac {d\phi}{dt} = -\frac {dB_{loop}}{dt}A = -\frac{d}{dt}(\frac{\mu_o}{4\pi}\frac {2\pi NR^2I}{(R^2+z^2)^{\frac{3}{2}}})A$$differentiating in terms of ##z##, we get $$\frac {d\phi}{dt} =(\frac{\mu_o}{4\pi}\frac {6\pi^2...

Hello Friends, I have been wondering, is it possible to construct a motor, and attach a coil to it, such that with the motion due to the rotation of the motor, it generates a excess of energy that can be used to power the motor in turn, basically, could i use the excess to charge a battery that...

To test an Experimental Model , my advisor said to make this investigation; I have a Reservoir of parrafin, Capacity is 50 liters, Around this Reservoir there is a Helical copper Pipe, I have to magnetize the Reservoir by using Helical coil . Many thanks For your assistance

Hej Guys, Did anyone see anywhere an equation to this? If nothing else then a loading time formula for solenoid would do. Thank you!

Hello all! I have made a Tesla coil using a proven circuit I found online but what I have made isn’t working here is a picture please help. PS: yes I know it is fairly messy but the specs are as fallows: B50k potentiometer One green 5mm led One 200ohm 1/4 W 5% resistor Primary coil is 8...

What would be the formula to calculate the right spacing distance between the coils in order to get a uniform homogeneous B field in the middle of the coils and how to determine the B field strength? I can only find bits and pieces on google about these sort of formulas but their intended for...

I need to buy a 'I' shaped CRGO laminated core sheets, is there any website where I can buy online? Thanks

The problem: a coil of radius r, length l and N turns, rotating with constant angular velocity ω around an axis perpendicular to its simmetric axis and passing for the center of the coil. The coils is submersed in a static magnetic field, intensity B0, perpendicular to the axis of rotation of...

Homework Statement A square coil (sorry, its not "current carrying" as shown in diagram, my mistake) of length L is released from rest, in a horizontal uniform magnetic field going into the plane of paper, of length 2L. What can you say about the coil's acceleration? Homework EquationsThe...

Homework Statement What is the necessary area for a generator that produces an emf of ##\mathcal{E} = 150V## when it spins at a ratio of 60 revolutions per second, in a magnetic field of ##B = 0.5 T##? Homework Equations ##\oint_{c} E \cdot dl = \mathcal{E} = -\frac{d}{dt}\iint_{s} B \cdot dS...

Homework Statement A coil has 460 turns and self-inductance 7.50 mH. The current in the coil varies with time according to i=(680mA)cos[πt/(0.0250s)]. What is the maximum average flux through each turn of the coil? Homework Equations ##\varepsilon_{ind} = N \frac{d\Phi}{dt} ...

I formulated a statement about the repulsion between a permanent magnet and an air core coil (electromagnets without a ferromagnetic or ferrimagnetic core), and I believe this statement is true, but I would like to seek the opinion of others about it: "In a system where an electromagnet made...

I want to make a dc generator and not sure my design will work. I will wind the coil on a donut shape disk and put 6 rectangular magnets on a disk rotor with North Pole face the coil. Please see attached pictures. Will this design works or have problems? Can I have one continuous coil or I...

This is a 12-0-12 transformer that I intend to use in my circuit: Why are there three wires in the secondary? One is of course the neutral (in black). Why are there two live wires? As an additional question, can I use four 1N5408 rectifier diodes to convert the output of this transformer to...

If I have a coil with 10 turns and a primary voltage $$V_p$$ and primary current $$I_p$$ and a single secondary coil with 10 turns, I understand the power in the secondary will be $$P=V_pI_P$$ and hence voltage and current in the secondary coil will be the same. If I now bring a 3rd coil with...

Homework Statement Consider a spiral of 20 turns with inner radius R and outer radius 2R. If the current is i, find magnetic field at the center of spiral Homework Equations From Biot-Savart law-dB=mu(idl)/4pi*x^2 The Attempt at a Solution Integration seems like a good option. x is...

Hi, I have a quick question. Say I have two metal rods or tubes and I want to make an electromagnet, one rod is with a diameter x and the other rod has a diameter of x2 (two times larger) Now I take the same gauge copper wire and wrap an equal amount of turns around each of the two rods. Then I...

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