Coils Definition and 188 Threads

In all the electric motors I have taken apart, the coils on the armature have never been insulated. This has always confused me because, how could the coil make a sufficient magnetic field if it shorts out to the adjacent wires from lack of insulation?

I have a discussion on how guitar pickup work, pickup is a coil with thousands of turns and magnet poles in the middle of the coil under each strings. My idea is the magnet poles magnetize a short portion of the string and when the string vibrates, it create a varying magnetic field. When the...

I am looking forward to a small project. For this i need some inductor coils. I searched through the local shops, but i could find any inductor coil. According to what i know inductor coils are made by making loops using wires. http://www.instructables.com/id/Making-a-Simple-Induction-Coil/ Is...

Please explain -- total electic field Ec + En within the coils must be zero Hi This is from the text University Physics. In pg. 1035, chap 10, in order to justify the use of Kirchoff's rule to analyze circuits containing inductors it is written : Let's assume we are dealing with an inductor...

Hi guys, This may be a daft question (or set of questions), but I just want to bounce a few ideas off the wall once I understand some simple issues. Can anyone tell me why if you pass a current through a wire in a magnetic field, the wire will move perpendicular to the both the current...

Homework Statement Two identical coils are parallel to each other on the same axis. They are separated by a distance equal to their radius R. They each have N turns and carry equal currents I in the same direction. Find an expression for the magnetic field strength at the midpoint...

Homework Statement We want to construct a solenoid with a resistance of 4.30 Ω and generate a magnetic field of 3.70 × 10−2 T at its center when applying 4.60 A of electrical current. We want to use copper wire with a diameter of 0.500 mm. If we need the solenoid's radius to be 1.00 cm...

Homework Statement http://img198.imageshack.us/img198/1421/vintm.jpg Given that k = 2 A) Draw in a qualitative manner the following letters Vin, VP, Vs, Uxy, UR1, UR2, UD B) Calculate the power in R2 C) Calculate the average current through R1 The Attempt at a SolutionI'll start with a...

I've been reading up on tesla's wireless power transmission lately, and I've been wondering how magnetic flux through the center of a toroid induces a voltage in its coils. From what I understand, the time derivative of magnetic flux through a loop is proportional to the induced voltage...

Homework Statement given two coils one with N1 rings legnth L1 the other N2 L2, one inside the other the radius is not given.. N1 is connected to battery V1 and N2 is connected to volt-meter what will show the volt-meter? (use N1,L1,N2,L2.V1) Homework Equations Faraday's law of induction[...

Hello. I just came to imagine a "thing" that I'm not able to understand correctly, so maybe you can help me. Imagine a high voltage source, and a circuit made of cable capable of handle high currents (with low resistivity) and a load with medium to high resistance (say 10 KOhm) Now you...

Homework Statement when the switch is closed , describe what will happen to the meter reading, the direction of the current flow, if any, and the magnetic fields produced in the two coils Homework Equations none The Attempt at a Solution the current flow is shown in the pic...

Hello Physicists, I am doing my final year of High School in Australia and our current topic is magnetism and related fields. Physics is my favorite subject after maths and I tend to query a lot of things. Here is my basic Idea: My basic instinct tells me that the orange wire must be...

Hi I'm suppose to find the direction of the magnetic field and the current in the diagram below and I was just wondering if I did this correctly. (red is magnetic field and blue is the current) Diagram: http://i324.photobucket.com/albums/k327/ProtoGirlEXE/100_0702.jpg And I have a few...

Homework Statement Compress air vessel has a volume of 10 ft3 .Cooling coils holds its temperature at 68F. The pressure now in the vessel is 100 psi. Air is flowing in at the rate of 10 lbm/hr.How fast is the pressure increasing? The Attempt at a Solution What I have done is...

Hi, I'm building a pair of helmholtz coils to do a variety of magnetism-related experiments. I've borrowed an old Avo Douglas coil winder and plan to do a couple of thousand turns on two sections of 50mm or 60mm diameter pipe. Some nylon threaded rod will pass through the middle of each coil...

This website is a great idea. (I'm a thread vergin) Not sure if its standard but where I live 'step up' is secondary = higher voltage Opposite for 'step down'. What would the result be if you connected one secondary with a high voltage and low current in series with a secondary that had a...

Homework Statement http://nplq1.phyast.pitt.edu/res/csm/csmphyslib/type66_inductance/PairOfCoils.jpg Coil A is a large 400 turn circular coil of radius 91.0 cm. Circular coil B has 160 turns, a radius of 2.0 cm and is located L = 92.0 cm from coil A along the same axis. The planes of the two...

Hello, I am working on researching new ways to insulate some scanning coils on the SEM I work on. Currently we use Kapton to insulate the wires but it becomes brittle and wears over time easily. I am looking for alternatives to using Kapton for the scanning coils. Any ideas and suggestions...

Homework Statement Two heating coils have resistances 12.0 ohms and 6.0 ohms, respectively. a)What is the Joule heat generated in each if they are connected in parallel to a source of emf of 115V? b) What if they are connected in series.Homework Equations Am I doing this question properly? The...

Hi, ***I just noticed this that I posted this in the wrong section thinking I was in the engineering forum...sorry!*** I'm designing a racking system to store sheet metal coils (see attached sketch). I calculated the I and S values required and according to my calculations, 4 x 4 x 3/8...

Hi there I'm engineering a suspension system with the damper consisting of a magnet going through some coils. As the energy produced from this is proportional to the velocity of the magnet, this would be ideal for an "energetic" damper. To calculate the damping coefficient produced, I...

Homework Statement We have 2 circular loops, each of radius R with current I in same direction. This is called a Helmholtz coil. The loop axes are along the z axis and the centers are at z=+/-s/2. Find the magnetic field along the z axis between the 2 loops. Homework Equations...

Why the values of inductance for an air-cored coil are not exactly the same for changing current across it in practice??

Homework Statement coils rotating in a magnetic field are often used to measure unknown magnetic fields. As an example, consider a coil of diameter 2.00 cm with 72.0 turns that is rotated about an axis perpendicular to the field at a rate of 20.0 Hz. If the maximum induced emf in the coil is...

I have a multistage coil gun. and i was wondering how exactly do u connect the coils together. lol i thought u take wire from the first coil and use that to start the second coil.

Hello everyone I am trying to simulate a three phase AC powered six coil stator ring using Multisim or Orcad. How would I do this? Would I use regular inductors as the coils or would I use coils with iron and steel rods inside them? Would I just connect each inductor coil pole pair...

Hello All, I have been doing some experiments with inductors of various sizes and inductances. I was wondering if anyone here knows of any suppliers out there that sell high impedance air-core inductors (a few thousand turns of high gauge wire (30 gauge or so)) that can be purchased off the...

I've already done an experiment to show that if I take two coils and connect the leads together I can physically move one magnet towards the first coil and it will draw a second magnet towards the second coil. Of course this depends on how you wire the coils together as it can also repel the...

Hello everyone: I am trying to find a program or formula that will help me figure out how many windings, turns of coil, are needed per coil on a 6 coil steel stator ring powered by 3-phase AC power to get a certain magnetic field strength, about 1.3T. Is there any way that you could help me...

I've been wondering about this for a long time. The little black box that you plug into the wall so you can power your electronic devices contains a general run-of-the-mill transformer. But if the power is completely shut off to the device: not draining any current waiting for a power button...

The multiple coils superconducting maget is uaually quench protected by bypass diodes. The heat spreading model is mentioned on textbook for coil to coil quench spreading. But the heat spreading is not fast enough for magnet quench protection. Because the theoretical quench protection...

Thanks it makes a lot more sense now!

http://i47.tinypic.com/k0n0gi.jpg i know that V1/V2=1/a I1/I2=-a how they interpret the left resistor to be like this ?

Why not all letters of the alphabet are used in loading coil distance? and why there is no pattern followed in the spacing designation?thank you very much...

Making Self resonating coils for wireless electricity transfer ! How to do @@ Dear Friends , I would like to make the wireless electricity project as done by MIT team.i am bit confused about how to make the two different coils resonate at the same frequency ?? Please help me... Thanks...

If I have a top view of two circular coils of conducting wire lying on a flat surface, what is the direciton of induced current that appears in the smaller coil when the switch in the larger coil is closed? I'm trying to figure out: 1.) which direction the induced current would flow through...

Homework Statement The figure shows a wooden cylinder with mass m = 0.100 kg and length L = 0.800 m, with N = 20.0 turns of wire wrapped around it longitudinally, so that the plane of the wire coil contains the long central axis of the cylinder. The cylinder is released on a plane inclined at...

Hi, I recently performed a stator core loop test and am now in the process of capturing the setup and results in a report. A short explanation of the test setup and execution: A cable is wrapped around the core and energized, which induces a magnetic flux through the core. The core...

Homework Statement The mutual inductance between two coils is 0.0100 H. The current in the first coil changes uniformly from 2.7 A to 5.0 A in 0.160 s. If the second coil has a resistance of 0.600 Ω, what is the magnitude of the induced current in the second coil? Please show stepsHomework...

i am planning to make a magnetic generator & i have a question : if i provide a disk with 12 numbers of neodymium (1x1”x1”cylinder) (n48) magnets around it , moving by motor clock wise at 1500 rpm , ( magnet specification: Br: 13.80- 14.20 KG, Hcb: > = 10.5 Koe, Hcj: > = 11 KOe ) the...

Some basic curve integration leads me to the believe, that if you stack two coils into one another with opposite identical currents and windings, their outside field cancels while the inside field is identical to the configuration without the outer coil. Is this correct and does this...

Homework Statement Two circular coils are concentric and lie in the same plane. The inner coil contains 110 turns of wire, has a radius of 0.010 m, and carries a current of 5.6 A. The outer coil contains 190 turns and has a radius of 0.014 m. What must be the magnitude of the current in the...

Homework Statement Imagine there are two parallel current-carrying coils, radius R, perpendicular to and centered on the x-axis, with centers at 0.5D and -0.5D. Both carry a current I in the same direction (clockwise). We would like to adjust D so that the magnetic field created by the coils...

How many coils ?? A coil is wrapped around a magnetic core of Relectance 12000at/wb. if the mmf is 1200 AT the determined flux how many turns is the coil if 2A were flowing threw it ? thanks, cs

I am trying to find out which combination of wire loop diameter and thickness produces the most current. The problem with thin wire is obviously that it has a lot of internal resistance, but it is easier to wind in more loops. Does anyone know for a fact if a certain gauge/thickness is the best...

Homework Statement The two solenoids in the figure are coaxial and fairly close to each other. While the resistance of the variable resistor in the left-hand solenoid is increased at a constant rate, the induced current through the resistor R will A - flow from a to b. B - flow from...

Homework Statement The coils in a set of Helmholtz coils have 186 turns and a radius of 15.9 cm. The current is set at 2.2 A. Express your answers in units of "T" for Tesla. a) Calculate the magnetic field along the axis at the center of the two coils (x = 0). b) What is the magnetic...

how do they improve high-frequency transmission (and not low-frequency?) ? I'm a biologist... Thanks

I'm trying to optimize pulse coils and determine power consumption. According to Ohm's law: P = V2/R where P=power / V=voltage / R=resistance Why isn't Ohm's law providing the same results as actual meter testing?? Testing coils with 1 "C" battery: 1.5 volts #1) 2.3 ohm coil...