Coil Definition and 864 Threads

Hello I want to calculate field of the Solenoid Coil with AC current. For a DC current field is calculated easily from the BiotSavart. What is the process for AC current? Get the L value with RLCMeter in operating frequency? Is there an equation to get the field with...

Hi! Does electromagnetic waves induced emf or current in the coil or inductor due to faraday law as the magnetic field is continously changing in em wave?

Homework Statement Not technically a homework problem, has arisen as a point on my A-Level specification and I'm a little unsure as to how they are seeing this situation. "Relate qualitatively the instantaneous e.m.f. induced in a coil rotating at right angles to a magnetic field to the...

If you have a cylindrical permanent magnet with a voice coil around it, sound moving the voice coil a small distance back and forth along the length of the bar magnet will produce an RMS voltage across the voice coil; but not very much RMS voltage if the voice coil is in the center of the...

http://img252.imageshack.us/img252/6080/photo46k.jpg Once the transistor is at cut-off, it means Ib and Ic = 0. I don't see what the diode has to do with anything in terms of "protecting" another component. Can anyone help me see that?

Why is it that a radio wave or a microwave is not affected by a magnetic field from a electromagnet or bar magnet? I know they are self contained and so no outside force should effect them but that I can't get my head around. The idea I have is that since the Electromagnetic field is...

Hello everyone I have coiled an electromagnet over the weekend using iron and magnet wire, but when I connect it to my power source, the electromagnet becomes very hot. Is there some coating I can use to reduce the heat produced by the electromagnet when in use? Like epoxy or some sort of...

Homework Statement This is more of a general question about magnetic flux in a uniform magnetic field, but I think this is the correct place to post it. I understand that magnetic flux through an area A is the product of the magnetic flux density B and the projection of area A onto a surface...

Hello i want to move an object with core magnetic filed.could you tell me how can i do that?and what is formula?

I have a question about a bilifar coil. First I need to set the image, You have a opposing bilifar coil so as to decrease the inductance of the coil. http://en.wikipedia.org/wiki/Bifilar_coil 1 Winding will be coil A and the other coil B just so we can all know which coil turn we are all...

Homework Statement A coil of wire has 600 turns and is 5.5 cm in diameter is in a magnetic field that decreases from 2.2 T to 0 T in 6.2 ms. The axis of the coil is parallel to the field. The coil is hooked up to two resistors of 120 Ω and 200 Ω connected in parallel. What is the maximum...

24. A square coil is perpendicular to a uniform magnetic field. Which one of the following would increase the magnetic flux through the coil? A. Decreasing the area of the coil. B. Increasing the number of loops in the coil. C. Removing the coil from the magnetic field. D. Increasing the...

I attached a problem from a practice exam. I'm stuck on part b). Part A, I'm assuming the answer is the standard equation for an infinite current sheet. How do I find induced current? I can only think of using Emf = NBA*ωsintωt Where Emf= I/R, but I don't have resistance. Only other equation I...

Homework Statement The Attempt at a Solution I now know the units are nWb. I'm just getting a little confused by answer. ((6.1mH)(7.3mA))/224turnes=.198795) (mH*mA)/turnes So would that equal= 198.795 nWb?

Homework Statement http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_s02_qp_4.pdf <------ CLICK ON THE LINK The Attempt at a Solution Is the above diagram the correct answer ? Please note that the diagram in the question paper is for COIL...

A 30mH solenoid inductor is wound on a form 0.4 m in length and 0.1 m in diameter. A coil is tightly wound around the solenoid at its center. the coil resistance is 5.0 ohms. The mutual inductance of the coil and solenoid is 60μH. At a given instant, the current in the solenoid is 0.3A and is...

NOTE : My Current question and source of debate is in post number 10. Lets say I have a square coil. I accelerate it in a direction such that it is perpendicular to a magnetic field directed into the page. As it enters the field and before it is completely in the field an...

Homework Statement A cylindrical solenoid 30 cm long with a radius of 8 mm has 400 tightly-wound turns of wire uniformly distributed along its length (see the figure). Around the middle of the solenoid is a two-turn rectangular loop 3 cm by 2 cm made of resistive wire having a...

Homework Statement Connect a battery to a solenoid A cylindrical solenoid 40 cm long with a radius of 8 mm has 250 tightly-wound turns of wire uniformly distributed along its length (see the figure). Around the middle of the solenoid is a two-turn rectangular loop 3 cm by 2 cm made of...

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 half a period. What average back emf is induced in the coil during this...

I've been trying to hash this problem out with some friends of mine, but we haven't been able to find a satisfactory answer: Tesla coils are (in an extremely basic sense) like a transformer. There are two coils of wire... the first one having a large current and not-so-large voltage. The...

Faraday's Law of Induction: EMF=-\frac{\partial \Phi}{\partial t} If two identical coil with same turns of wire and same dimension ( same cross section area in the middle), one has only air and the other has a magnet core. If the two placed in an uniform varying magnetic field, is there...

Hi everyone, I am trying to figure out how to correctly calculate the self capacitance of a multi layer coil. I have been trying to find an online calculator or software which can do this but I don't really know where to look. Just hoping someone here can give me some insight. Any help...

Homework Statement a positive point charges q= +8.00 μc and q'= +3.00μc are moving relative to an observer at point p (midway between the charges) the distance from on charge to the point is .12 m and one charge moves to the right at 4.5 x 10^6 m/s while the other moves to the left at 9.00 x...

I am designing a coil which will have 2100 turns of 30AWG wire. The bobbin diameter is 1.045" and the length is 1.28" From my calculations I will use about 8,420 inches of wire. I tried an online calc but they did not take into account that the wire I am using has a heavy insulation so it's...

hey guys ,, how are you all ?? guys , I've got the following problem , Air enters a gas-fired furnace at 20deg at a mass flow rate of 0.2kg/s and is burned with an air-fuel ratio by folume of 12. the gases leave the furnace at 350deg. A run-around coil system is installed to recover some of...

Homework Statement A rectangular coil of 90 turns has dimensions of 22 x 65 cm and is located in a uniform 1 T magnetic field. In 1.7 s, the plane of the coil is rotated from a position where it makes an angle of 19° with the magnetic field to a position where it makes an angle of 64°...

I am about to build an induction coil in the traditional manner, after "A. T. Hare". The dimensions intimated in the book are confusing and imply there are 96 pies 3/16" each or 18" long - this is the length of the core, and the book indicates around 13" between ends of coils. The book also...

I am making a coil gun for my high school physics project and I am running into some issues. I am using 400 turns of 36 gauge wire wrapped around a 1.25in diameter PVC pipe to propel a 1 inch diameter steel ball. I started with a 6v battery but that didn't move the ball at all even with...

I apologize in advance if some of my answers don't quite make sense. I'm generally articulate, but not when it comes to physics I'm barely grasping. I did a lab and part of it was dropping a magnet through a coil, which produced a Voltage vs Time graph using LabPro. For trial 1 we had the N...

Hello!I'm working on an experimental alternating current generator project and need specific equations to calculate voltage and current output from a permanent magnet driven inductor, so I will have an idea what to expect before I commit real money to expensive materials. the only variables...

Homework Statement A closely wound rectangular coil of 95.0 turns has dimensions of 29.0 cm by 40.0 cm. The plane of the coil is rotated from a position where it makes an angle of 39.0 degrees with a magnetic field of 1.60 T to a position perpendicular to the field. The rotation takes 0.120 s...

could you please give me an build structure or the standard model of it's blueprint. Thank you ... Be Ω Thik Ω ! :)

Ignition Coil Won't Spark from Mosfet but DOES spark By Hand? HELP!? I'm trying to get an ignition coil to create sparks running it with a Mosfet powered by a 555 timer. The Mosfet is definitely switching. I checked it with resistor, ampmeter, and o-scope. Everything is behaving predictably...

Hi, I am looking for a formula that calculates self inductance and capacitance of rectangular spiral coil, i came across many formulas for helical coil and circular spiral coil but couldn't find one for rectangular coil, any help is highly appreciated. Thanks

On several occasions, I've seen the demonstration where a person holds a fluorescent light bulb up to a tesla coil, and it illuminates. And in general, demonstrators don't seem too worried by the sparks generated. But I was looking at this page, http://www.pupman.com/safety.htm and was...

I am interested in replicating Bob Beck's work in the attached PDF document, dating back to 1978. After building a variety of coils Beck was able to demonstrate EEG entrainment with a 9-foot coil and by broadcasting an amplified Schumann Resonance frequency. The idea would be to interface said...

Homework Statement A water heater consisting of a metal coil that is connected across the terminals of a 24-V power supply is able to heat 270 mL of water from room temperature (20°C) to boiling point in 70 s. What is the resistance of the coil? (When entering units, use ohm for Ω.)...

Hello everyone, I am trying to make a coil with the exact specs as the original. I have all the info I need except the actual core material used. I have all the measurements of the core and coil including: Wire gauge, # of turns and turns per layer,Bobbin dimensions, inductance without the...

So, how do Oudin coils differ from Tesla coils, and how do they operate? All I have been able to determine is that the primary coil as well as the secondary coil is grounded, and that the primary and secondary seem to be one and the same, although I'm not even sure about that. Every website I...

I am in need of a transformer which has the following characteristics: Operating frequency 20kHz Turns Ratio 1:8 Primary 12V square wave @ around 100mA max Dual secondary coils (wound together with equal turns) (Note: Only 1 secondary coil will operate at any given time) Secondary 96V...

Hi All, I am at present working on coil design for RFID tag, i want to know how you add capacitance in spiral coil i.e. how you join two ends in spiral structure with capacitance in between, i have already calculated capacitance value needed to resonant at particular frequency. Any help is...

What keeps the current in an electromagnetic coil from moving between the touching conductors and instead go through the conductor? Is it the resistance being much higher between two touching sections of the coil? Is there a small amount of current "leaking" between each loop where they touch?

Homework Statement To determine the Specific heat of an oil , an electrical heating coil is placed in a calorimeter with 380g of the oil at 10C. The coil consumes energy(and gives off heat) at the rate of 84W. After 3min the oil temperature is 40C. If the water equivalent of the calorimeter...

Apparently, that's how a lot of car speedometers work... but I don't understand how a rotating magnet inside a coil (or any conductive material, really) can induce a current in the coil. I can understand how pushing a magnet in and out through a coil can induce current, because Flux = Area...

Homework Statement A series circuit consisting of a 10 ohm resistor, a coil and an ideal capacitor is connected across a 200 V, 60 Hz power supply. The current drawn is 8 A. The voltage across the coil is 120 V and its power factor is 0.8 lagging. Determine (a) the voltage across the...

Hello everyone I have a quick question on how to wind overlapping layers of magnet wire around a coil form. How do you layer coil turns for a coil? Do you just start at the top of the coil form and then coil over the top of the previous coil in the same direction and then just twist the two...

Homework Statement A cylinder with mass m = 262 g and length L = 12.7 cm has a wire longitudinally rolled up around it, such that the rolling plane, with N = 13 turns, contains the axis of the cylinder and is parallel to a plane which has an inclination θ with the horizontal. The cylinder is on...

Magnetic bullet fired through a coil can fire another bullet (no amplifiers, batteries, etc. are involved) A magnetic bullet, fired through the middle of a coil, can induce enough current that a nichrome wire connected to the ends of the winding gets hot red and is able to ignite a charge of...

Hi! I'm stuck on a problem concerning the magnetic field produced by a long straight conductor: A triangular piece of conductor (N=1) rests in the vicinity of a long straight conductor with a current I=50A. What is the magnetic flux through the triangle if a=1cm? (See attached file). My...