What is Inductance: Definition and 494 Discussions
Inductance is the tendency of an electrical conductor to oppose a change in the electric current flowing through it. The flow of electric current creates a magnetic field around the conductor. The field strength depends on the magnitude of the current, and follows any changes in current. From Faraday's law of induction, any change in magnetic field through a circuit induces an electromotive force (EMF) (voltage) in the conductors, a process known as electromagnetic induction. This induced voltage created by the changing current has the effect of opposing the change in current. This is stated by Lenz's law, and the voltage is called back EMF.
Inductance is defined as the ratio of the induced voltage to the rate of change of current causing it. It is a proportionality factor that depends on the geometry of circuit conductors and the magnetic permeability of nearby materials. An electronic component designed to add inductance to a circuit is called an inductor. It typically consists of a coil or helix of wire.
The term inductance was coined by Oliver Heaviside in 1886. It is customary to use the symbol
L
{\displaystyle L}
for inductance, in honour of the physicist Heinrich Lenz. In the SI system, the unit of inductance is the henry (H), which is the amount of inductance that causes a voltage of one volt, when the current is changing at a rate of one ampere per second. It is named for Joseph Henry, who discovered inductance independently of Faraday.
I only know that apparent inductance = Phi/I, incremental inductance = dPhi/dI.
Two definitions because of the non-linearity of Phi vs. I curve.
So is there anyone who can tell me when I should use incremental inductance and when apparent inductance?
Many thanks.
http://www.youtube.com/watch?v=o0hXYfvnND0
What would happen if the ground was kept in place and the positively charged rod was constantly moved to and away from the electroscope? Would we not have ac current between the Earth and the electroscope?
Replace The electroscope with a capacitor...
A series RLC circuit connected to a 100-V 60-Hz source draws a current of 2.5 A. The
measured power factor for the circuit is 0.7 leading, and the inductive reactive power is
300VAr. Calculate the resistance, inductance and capacitance of the circuit and show the
corresponding impedance...
So I know transformers work by mutual inductance. A first loop that is connected to AC current produces an alternating B which produces a changing flux. As a result an induced Emf is formed. This Alternating B is also alternating in the second coil as well to produce same emf (if same number of...
Could anyone help me to find out a book which has detailed explanation(derivations) for the capacitance, inductance of a mictropstrip line. It would be helpful if the book has detailed discusions on fringing fields,(effective width of the ground plane) effective permitivty etc.
I have tried...
Homework Statement
For one of the problems in my homework it asks to prove that L=μAN^2/length ...i didnt have a problem with that osrt but the second part states a spring is 5cm long and has a diameter of .15 cm with 50 coils...how much self-inductance must you include for it to model as an...
Homework Statement
I am supposed to find the circuit design for a first-order low-pass filter. The filter must be made of resistors and capacitors only (no inductances). Furthermore, the output voltage must be measured over a resistor or something in parallel with a resistor.
Homework...
Homework Statement
This is more to do with an experiment I'm failing terribly at rather than a direct homework question. I could not find the right section to ask this in.
Investigate the inductance of inductors with cores of Perspex and Copper using an Anderson's bridge. For Perspex, compare...
The problem I have is the following:
Two Coils have a resistance of 25 ohms and an inductance of 20 mH. Coils are mutually coupled with a coefficient of coupling of 0.6.
(a) Calculate the voltage input to the first coil to develop a power of 1.6W
at a frequency of 1 kHz. with a load of 55<-40...
Homework Statement
So in Walter Lewin's Electricity and Magnetism video series:
http://www.youtube.com/watch?v=UpO6t00bPb8&feature=relmfu
At around 10:00 he says that the resistance in the self inductance is zero because self inductance is superconducting material. However is it possible...
Homework Statement
See attached.
Homework Equations
The Attempt at a Solution
(5+j8)I1-j6I2-j3I2-j3I1*2=magnitude(12) degrees (60)
(5+j2)I1-j9I2=magnitude(12) degrees (60)
j2I2-j6I1-j3I1=0
-j9I1+j2I2=0
I put these equations into mathematics software and get the answers...
Homework Statement
A solenoid is wound with a single layer of insulated copper wire of diameter 2.100 mm and has a diameter of 3.000 cm and is 1.900 m long. Assume that adjacent wires touch and that insulation thickness is negligible.
a) How many turns are on the solenoid?
Solved...
Homework Statement
The ignition coil supplies V=20kV to the spark plugs.
The maximum current in primary coil Imax=4.0A.
The current is interrupted 100 times/sec by the distributor points.
Estimate the mutual inductance M of the primary and secondary coils.
Hint: I have to make a...
Hi, I was reading some text and came across this problem, the problem is also mentioned in this link from Wiki: http://en.wikipedia.org/wiki/Inductance#Self-inductance
They said that it is because the 1/R now becomes infinite, this is what I'm confused about. From my understand, there would be...
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...
any help would be much appreciated
i am trying to calculate the inductance and impedance of a unknown air cored inductor. over a set frequency range (1600hz - 2700hz in 100hz increments) using a series RL circuit
tools
scope
multimeter
frequence generator
Amplifier
1ohm 100W metal...
Hello. I am working through the book "Analysis of Electric Machinery and Drive Systems" by Krause. On p.51, the mutual inductance between two windings (a and b) of a 3-phase machine (generator) is calculated. I am struggling to follow the integration performed on eqn 1.5-15 to arrive at eqn...
http://img638.imageshack.us/img638/989/newbitmapimagety.png
I am running my loop current equations for this circuit and have.
-1+-j6*(I1-I2)=0
-j6*(I2-I1)+j20*I2 +j12*I3=0
(j30-j2+j5+4)*I3+j12*I2=0
But i am being told that the mutual inductance term j12 should be negative in both.
My...
*This isn't a problem so much as needing to fill in the gaps from a lecture where I was taking notes on painkillers due to surgery. The problem statement is my best guess as to what exactly was said by the instructor.
Homework Statement
"Find the mutual inductance (M) of a square-bore...
Hi
I'm doing simulations in preparation for experimental measurements of decoupling capacitor parasitic inductance. I've done simulations of two port measurements, in mentors hyperlynx, of parallel capacitors on small power planes. These have given me s2p files that I've converted to...
Hi All,
I have a component that at 1 Khz has 100 mH Inductance and 100 Ω resistance.
I know that at higher frequencies which I will need to run the circuit, these values won't be the same anymore.
Is there any way, mathematically, to figure out what those values would be at higher...
Friends:
I would like to verify my understanding of mutual induction.
Coil 1: n1 turns per unit length, radius is r1, has a current I1
Coil 2: n2 turns per unit length, radius is r2, has a current I2 (in the same direction as I1)
r1 > r2. Coil 2 is inserted inside Coil 1. What is the...
Friends:
Lets say you have a conductor that is made of two components - an inner core of steel and an outer layer of aluminum (ACSR). Is there mutual inductance between the steel and the aluminum? Every example of mutual inductance I have seen requires that an insulated wire be wrapped around...
Homework Statement
The Attempt at a Solution
Just was hoping someone here would be able to help me with the circuit above. I wanted to ensure that I analyzed it properly.
I applied Ohm's Law to determine the initial current through the inductor. i(initial)=-16V/2.2kΩ=-7.27 mA...
If we know the inductance of an iron-cored coil to be 200mH, and we remove the iron core such that the core is now air, how exactly can we determine what the new inductance is with just this information?
I played around with the equation for inductance, however, I could not seem to get it...
Homework Statement
The graph below shows the voltage across a 820 mH inductor vs. time.
Find the current (Ix), the power delivered (Px) and the energy stored (Wx) at time tx = 9 μs.
The attempt at a solution
I tried adding up the areas of the rectangles up to tx and multiplying it by...
Hello. I'm am studying topics related to inductances and Faraday's law and I'm having hard time at PICTURING situations. Mental representations.
So I propose an example of something I don't understand and we may go on from there.
Consider circuit consisting of an inductance and an AC source...
When an inductor is oscillated at it's resonant frequency it becomes a parallel LC circuit (Tank circuit). At this frequency the circuit has a theoretical infinite impedance.
However, due to the resistance of the inductor energy is dissipated. The power supply provides a small current (equal...
In an a.c.circuit containing only inductance, for example, it is said that the current is lagging behind emf by 90 degree. We can understand this that when the emf is zero,the current is at its negative maximum and when the emf reaches its positive maximum, the current becomes zero and so on...
Friends:
I have been thinking about this question for a while, so I hope you can help! Here it is:
Lets say you have two concentric, conducting cylinders.
The outer cylinder ("Cylinder 2") has the following properties: radius R2, carries a current of I2, relative magnetic permeability...
Homework Statement
Find the coefficient of mutual inductance between the twin lead and square circuit if they're being circulated by currents I1 and I2 respectively. Also find the interaction energy and force between the two. See image
[PLAIN]http://img94.imageshack.us/img94/1277/induct.png...
Hi all!
I tried to make an inductor.
Naturally, I am not sure about it's inductance value.
I made an LC series circuit on a bread board.
I am using a oscilloscope and an a function generator to find the value of L during the resonant frequency. Channel one goes from function generator...
im trying to understand the mutual inductance in induction motor operation...How the mutual inductance occur in induction motor? what it does with the rotating magnetic field?
I am wondering, In a flyback inductor used for a boost converter, what inductance would be required to produce 5kV across the flyback inductor in 1mS with a current of 10mA?
I know the formula would probably be V=L di/dt but I'm not sure how to rearrange it to get the correct answer.
Hi all, I'm studying computer aided design at university but i have to complete an electronics module. My knowledge is extremely basic and my lecturer 'does not have the time to go through basic physics' so i need a little help.
I have been asked to...
'Design a coil which has a given...
Homework Statement
A coil of self inductance L_{1} is coupled to a second coil of self inductance L_{2} and resitance R. The coefficient of mutual inductance is M. The second coil is short circuited whereas the first coil is connected via a switch, to a voltage source V_{0}cos \omega t...
Homework Statement
A 50 mH inductor, a 10 microF capacitor and a 200 ohm resistor are connected in parallel. A voltage of 10 v at 1kHz is applied. what is the magnitude of current that flows?Homework Equations
The Attempt at a Solution
I recognised this would be a problem where i would need...
Homework Statement
Consider two rectangular loops. An outer and inner loop. Assign outer loop a length a and width b. Assign inner loop length c and width d.
Apply a current to the outer loop.
Determine an expression for the mutual inductance between the loops.
Homework Equations...
A solenoid has a radius R, length L, with N turns and carrying a current I. If a cylindrical rod with permeability μ and radius R/2 is inserted inside the solenoid, what is the inductance of solenoid?
This problem is tougher than I though and I'm stuck on a couple of things.
Homework Statement
There are 2 inductors, a DC power source, 2 resistors, and a switch. The circuit looks just like the image I've attached, except it will have a switch on the left of the first resistor and the...
Im working with building a reluctance motor and I've posed a problem to myself that i cannot answer without questioning some long accepted facts about the inductance of a solenoid.
The simple solenoid and toroidal solenoid are two shapes that seem to have simple equations for calculating the...
Homework Statement
Suppose a fixed distance separates the centers of two circular loops. What relative orientation of the loops will give the maximum mutual inductance? What orientation will give the minimum mutual inductance?
Homework Equations
none
The Attempt at a Solution...
Homework Statement
An inductance of 3 mH has the following voltage waveform: for 0<t<2\text{ }ms, v=15\text{ }V; for 2ms<t<4ms, v=0; and for 4\text{ }ms<t<6\text{ }ms, v=-30\text{ }V. Assuming i(0)=0, find the current at time (a) 1 ms, (b) 4 ms, (c) 5 ms.
Ans. (a) 5 A; (b) 10 A; (c) 0Homework...
Find "max. stored energy" (in capacitance and inductance)
1.) I'll start with capacitance since I get closer to solution (than in inductance problem). :redface:
First get the voltage v(t)=\frac{1}{C}\int i(t)dt=\frac{1}{C}\int \frac{V_m}{R}e^{-\frac{t}{RC}}=-V_m e^{-\frac{t}{RC}}
Now...
In the flyback inductor equivalent circuit and also in general, why is magnetizing inductance represented in parallel to the actual inductance?
We can have just the Magnetizing inductance in series with the leakage inductance.
Also, in flyback converters why does the secondary voltage get...
Find the inductance per unit length of parallel plate tx line width = w and space =d between the two plates. w>>d.
My question is whether the total inductance is twice the calculate inductance because total inductance is the sum of inductance of the top and the bottom plate. But it seems all...
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...
Hey Folks. I am currently designing a buggy which tracks an inductive wire using two inductor sensors. The wire is carrying 20Vac pk-pk , 125ma at 10kHz. I have designed a sensor circuit which has a ratio of 2:1 ie it outputs a waveform of 10Vac pk-pk (assuming 100% mutual inductance). This is...