Inductance Definition and 460 Threads

My old freshman physics text defined inductance as flux/turns, which applies only to solenoids. This seems like a pretty weak definition since any length of wire in any geometry has some inductance. There has to be a more general definition. My first guess was that L could be calculated from...

I am designing a loop antenna and would like to calculate the inductance. The radius of the loop is 6.67 centimeters, the radius of the wire is .42mm (#26 awg) and has 57 turns. Using the following formula L =N^2*R*mu_o*mu_r*(ln(8R/r)-2) where N=turns, R=loop radius and r=wire radius. From...

I am trying to design UHF quadrature couplers from the following references: [1] 'Broad-Band Twisted-Wire Quadrature Hybrids' , http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1127996 [2] 'Twisted wire Quadrature Hybrid Directional Couplers' QST Vol 63 January 1978 pages 21-23...

Homework Statement A single rectangular loop is placed distance C from a wire of current I. The dimensions of the loop are BxA. The loop and wire both lie in the same plane, and a is at right angles to I. Derive an expression for the mutual inductance, given that you found flux in a previous...

Hello, I need help with calculating inductance of a toroid core. I tried googling and came up with 3 results, but they don't really help. Links are: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/indtor.html http://www.nessengr.com/techdata/toroid/toroid.html...

Homework Statement An electric motor draws a 1A (rms) from the 230V (rms) mains. and is found to shift the phase of the 50Hz alternating current by 30% of the period. What is the self inductance of the coils in the motor? Homework Equations The Attempt at a Solution i've started...

Homework Statement Pulsed lasers used for science and medicine produce very brief bursts of electromagnetic energy. If the laser light wavelength is 532 nm, and the pulse lasts for 37 ps, (a) how many wavelengths are found within the laser pulse? (b) How brief would the pulse need to be to...

When finding for "L" is the value for "l" (length of coil) affected by the length of the core material. Or more specifically when one is working this equation for two coils yoked in series do you figure each coil separately?...and if NOT, do you include the length of the yoke? Here is a link...

Homework Statement The oscillator of a 96.9 MHz FM station has an inductance of 1.4 μH. What is the value of the capacitance? Homework Equations I haven't the slightest idea. I've looked through the section in my physics book and looked all over online and I can't find anything. The Attempt...

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

If I have a trace on a PCB that is wider on the left side and then tapers down to a narrower trace on the right side, why is it that the inductance is greater on the narrower side? I realize there are equations that describe this behavior but I'm just trying to get a qualitative understanding of...

Hi everyone. I was wondering about something I just read with wireless energy transfer and resonant energy transfer on Wikipedia.org. What if you send a large amount of ultrasound tuned to a certain frequency over the AC/DC outlet plug. Would it get to the Transformer? Would the transformer's...

What is the relation between the coupling coefficient and the fraction of flux from one inductor going through the other inductor?

Consider a solenoid which is almost toroidal, with a few turns missing (say you have 1000 turns on 99% of the circumference of the toroid) - they will form the primary winding. Let us have 10 turns on 1% of the circumference of the toroid - they will form the secondary winding. Since practically...

According to widely known formulas, the inductance of a long straight solenoid will remain practically the same if we bend it into a toroidal solenoid. It seems to be a contradiction, because the magnetic path length of a straight solenoid is more than two times greater.

NOTE: This is not a homework problem, so do not shift it. The question is as follows, I am given a core having an air gap wounded by a coil, I am given area of core, gap. Length of core and gap. number of turns. Permeability of core and air gap and magnetic field in the core (I assume no...

I posted this question a few months ago, but got no responses, especially after it got moved to the homework help forum. Since then, I have asked several professors, many of whom I expected to be experts in this area, and I've been given several different shaky sounding responses. So, I'd like...

Consider two solenoids, an often familiar formula for the induced emf from 1 solonoid in the 2nd solenoid is [PLAIN]http://http://www.mediafire.com/?ymfmhzjgqkgenjz. My question is. Doesn't this only account for the emf induced in solenoid # 2 from solenoid #1, and not the emf induced in...

Can anyone explain the concept behind changing of inductance of a solenoid (when AC current is passing through solenoid) on moving a metal sleeve (hollow metallic pipe) over the solenoid enclosing the solenoid.

I've been working my way through an old scientific paper on inductance calculation, and there's a fundamental principle I'm having a problem with. Suppose there are two filamentary conductors of any arbitrary shape. Now consider an infinitesimal element dl1 somewhere on the first conductor...

I have a very basic question regarding mutual inductance. Consider a basic square loop with two coils wound on opposite sides from each other, with coil one excited while coil two si left open circuited. The total flux linking coil 1 is Φ11 = Φl1+Φ21 where Φ11 is the total flux...

I was recently given a problem I can't quite wrap my head around. Here's the situation: shttp://pics.bbzzdd.com/users/theman/inductorbulbs.gif (you'll have to copy the link, - the s, into your address bar) Oh-- and i just realized a mistake with the drawing, the dots should be x's to...

i am having trouble with finding inductance and capacitance of a cylindrical shell with gap. say inner radius is a, outer radius is b, and filling dielectric between a and b, and its not a exact circle which have a small gap say d. its like a split ring but only one shell. How can i...

Hi, Hope this is the right forum to ask this question. I have an electric fence running parallell to an electrified railway (25kV@50Hz, varying current). I'm trying to figure out how to calculate the induced voltage on the fence to figure out how long the fence can be before it becomes...

While working on a project I noticed something wonky and I don't understand how or why it is happening. Typically if I have an inductor, the presence of a permanent magnet will reduce the inductance according to its distance - however I have started using a type of nanocrystalline core that...

Homework Statement One solenoid is centered inside another, The outer one has a length of 50cm and has 6750 coils, while the coaxial inner solenoid is 3cm long and 0.12cm in diameter and contains 15 coils. What is the mutual inductance of these solenoids? Homework Equations M=N1\phi1/I2...

Hi all, The situation is this: I need to calculate the self inductance of two solenoids wired in series, of equal radius and a given separation d. They are coaxial. The length h of each is known. Most double-solenoid references I found looked at the mutual inductance, and not the...

Homework Statement Hello, I am currently doing an investigation to study the factors affecting inductance. The three variables i am using are the number of turns on the coil, the material of the core of the coil and putting 2 cores in series/parallel to see how this affects the inductance...

Homework Statement A typical "light dimmer" used to dim the stage lights in a theater consists of a variable inductor L (whose inductance is adjustable between zero and Lmax) connected in series with a lightbulb. The electrical supply is 120 V (rms) at 60.0 Hz; the lightbulb is rated as 120...

ok, let's say we have a battery connected to a resistor and an inductance in series -|battery|+______ 00000(inductor)______resistance(R) if the rate of change of current is decreasing , then the induced EMF in the inductor would be towards the right? because they would want to strengthened and...

Homework Statement The current in a 4.70 mH inductor decays over time according to the following function, where t is in seconds. I(t) = (.943A) e-(396 s-1) t) (a) What is the induced emf across the inductor at t= 5.00 ms? (b) How long does it take the emf to drop below 1.25 mV?The Attempt...

what is inductance?...i need a physical meaning and not equations!

Hi. This is a question from my lab. I have a series of measurements of the voltage drop across a resistor for various frequencies with a constant voltage source in an LR series circuit. From these measurements I am supposed to calculate the value of the inductance "L". How can I do this?

Homework Statement A long solenoid (black coil) with cross-sectional area A cm^2 and length L is wound with n1 turns of wire. A time-varying current i1 flows through this wire. A shorter coil (blue coil) with n2 turns of wire surrounds it. Use (uo)(m*kg/s^2*A^2) 1) Find the value M of the...

Homework Statement Determine the inductance of a solenoid with 650 turns in a length of 21 cm. The circular cross section of the solenoid has a radius of 4.2 cm. Homework Equations ? The Attempt at a Solution I've looked all over my textbook and can't come up with a possible...

Homework Statement The stator of the magnetic circuit of the above figure has a coil of turns 200, which carries a current of 1A. The rotor has a radius of 30mm, a height of 30mm and an axial depth of 20mm. The material for the stator and rotor has infinite permeability. The air gap...

Homework Statement An RL circuit has a 9.0 V battery and a 5.5 ohm resistor. When the switch is closed, the current in the circuit is observed to increase from 0 to 0.30 A in 0.17 s. A) What is the inductance? B) How long after the switch is closed does the current have the value 0.47 A...

Homework Statement Find the inductance L. This is for a lab experiment. For a resistor-inductor series circuit, I have a graph of a triangular input waveform from a generator and the voltage across the inductance, VL, as a function of time. I also have the value of the resistance R. The...

Homework Statement If the outer conductor of a coaxial cable has radius 3.5 , what should be the radius of the inner conductor so that the inductance per unit length does not exceed 55 per meter? Homework Equations The Attempt at a Solution 1.385

I am about to do an investigation on the 'factors affecting inductance.' It would be brilliant if anyone had any ideas on experiments I could perform to investigate the factors affecting inductance. Thanks for your time.

Determine the value of the inductance ...?? Homework Statement Consider a series RLC circuit. The applied voltage has a maximum value of 210 V and oscillates at a frequency of 76 Hz. The circuit contains an inductor whose inductance can be varied, a 900 ohm resistor, and a 1 μF...

Homework Statement A circular coil has a radius 0.10 m and 30 turns. An external magnetic field 2.60 mT is perpendicular to the coil. a) If there is no current, find the magnetic flux in the coil. b) When current = 3.8 A in some direction, there is no more net flux in the coil. Find the...

Inductance of the coil?? Homework Statement A radio has a tuning circuit consisting of a variable capacitor and antenna coil. IF the circuit has a maximum current when C=300pF and f=40kHz, what's the inductance of the coil?? Homework Equations f= 1/(2pi root (LC)) The Attempt...

Homework Statement A circuit consists of a capacitor and an inductor. The resistance in the circuit is small and can be neglected. Initially, at t = 0 s, the voltage across the capacitor is at its maximum of VC = 10 V, the charge stored in the capacitor is 1 mC. It is observed that the...

So I've been working on this for a while now, but I'm a little stuck. I think I see how to solve the problem below, just need a couple tips to get me over the hurdle. Homework Statement There are two infinite wires in the same plane as a rectangular loop. Geometries are displayed in the...

URGENT!: Self and mutual inductance Homework Statement 1http://img20.imageshack.us/img20/8531/asdasdasv.png a) Calculate L1, L2 and M for the coils in the following toroid (using thin toroid condition), the induced EMF in the second coil and the polarity. N1 = 500 N2 = 200 I1 = (20 +...

I am working on determining the mH needed to produce a 250 gauss (0.025 T) magnetic field by a flat coil in a 8 ohm audio circuit that is PC controlled with an NHC tone generator. I need some help to do so as the information that I am able to get online does not allow me to make the jump from...

This is not a homework problem, but practice. I have the answer. I need to know why. Homework Statement Homework Equations i=\frac{E}{R}(1-e^{\frac{-t}{\tau}}) "charging" an Inductor The Attempt at a Solution I have solved part a) correctly...

pic : http://s982.photobucket.com/albums/ae310/christianerik/?action=view&current=untitled.jpg If the switch is closed at t = 0, find the current in the inductor at t = 0.224 s. Answer in units of A. & Find the current in the switch at that same time. I know that i must use i = V/R(1 -...

If the switch is closed at t = 0, find the current in the inductor at t = 0.224 s. Answer in units of A. & Find the current in the switch at that same time. I know that i must use i = V/R(1 - e^-t/L/R) but can't seem to get the right answer. Any help is appreciated...5 ohms...