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.
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...
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...
Homework Statement
http://img265.imageshack.us/img265/8616/43354308.png
I have an exam coming up in a few days and I am doing some revision questions from some past exams and this is one I have attempted but I have no solutions to check my answers.
The Attempt at a Solution
using Vs = 12cos(...
Homework Statement
Homework Equations
E=-M\frac{di}{dt}
The Attempt at a Solution
Can anyone even tell me what the heck this problem is asking? This chapter has been a nightmare and I don't understand any of it. The book is terrible and barely explains what 'mutual inductance'...
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...
Homework Statement
demostrate that the self inductance of a selonoid (L) that have: length = "l"; radius= "a" ; number of turns per unit of length= "m" , is:Homework Equations
L = pi*(m2)*(a2)*Uo*[ ( (l2)+(a2) )1/2) - a ]The Attempt at a Solution
It is suposse that the selfinductance is just...
pic : http://s982.photobucket.com/albums/ae310/christianerik/?action=view¤t=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...
Homework Statement
A motor has both resistance and inductance. A motor rated at 1 hp input operating at 240 V draws 4 A of current because
a. power is lost due to resistance
b magnetic saturation robs power
c. inductance does not consume power
d. friction in the bearings of the motor
e...
Homework Statement
A mutual inductor consists of two coils X and Y arranged so that one quarter of the magnetic flux produced by X links with Y. When X is used as the primary coil and Y as the secondary, the mutual inductance is M. What is the mutual inductance when Y is used as primary coil...
Mutual inductance as a psuedo-capacitor?
1. I am testing how reduced the mutual inductance btwn two parallel ring-shaped inductors is when a material is placed btwn them. The primary coil is connected to an AC generator in series with an ammeter (on the order of mA), and the secondary in...
Hi, I would like to ask a question about Mutual Inductance and Transformer.
Suppose I have two coils N1 and N2, where N1 is the primary coil and N2 is the secondary coil that is connected in series with some resistance Rx. If I place a voltage V1 across the primary coil, the output voltage V2...
Homework Statement
An inductor has the form of a coil with 2074 turns and a diameter of 1.9 mm . The inductor is placed in a magnetic field perpendicular to the plane of the coil and increasing at a rate of 0.48 T/s . The current in the inductor is zero at t = 0, and then increases to 6.9...
Ok so i understand that after a switch in a circuit is closed for awhile the inductor acts like a battery, however, what happens after the switch is opened after being closed for awhile.
A review question asks whether the energy:
- is converted to sound and spark
- remains stored in the...
Hi,
when summing the votages when using Kirchoff's voltage law around some loop, why do anywhere they take L(dI/dt) as the voltage fall on the inductance (if we sum the voltage in the current direction)?
If I understand well , if there is a current in some direction, the induced voltage...
I need the inductance of a simple ferrite core wire-wound inductor.
It's not clear how to get than in 2D Maxwell SV.
The core is one material (ferrite), the windings are another (Copper).
If you group them, the group must be of a single material, so no good.
If you don't group them...
Homework Statement
Hello I am studyin for a test and I just wanted to make sure I understand this basic idea...
All C's are 5 micro F
All L's=2H
Homework Equations
The Attempt at a Solution
For the I came to the conclusion that Ceq=5 micro F
the ones circled in blue...
i am having a doubt that when we find a expression for mutual inductance we say that flux change in primary coil induces emf in secondary coil. but why change in flux doesn't induce any current in primary coil also.
http://i26.tinypic.com/250tkyh.jpg
the formula for magnetic field
is like they show but its not divided by l
like they did
i can't see a reason why they present it that way
??
Homework Statement
A constant current of 1A through a solenoid creates a magnetic flux of Φ=20mWb measured on the solenoid axis in the middle of the solenoid. What is the value of the solenoid inductance?
Homework Equations
here's what I've managed to find on the subject...
Ive made an experimental generator built loosely of the Faraday flashlight technology. Rather than a linear air coil using a reciprocating magnet I've made a toroidal coil and added magnets on the outside of the toroidal to coerce unidirectional movement of the interior magnets that match the...
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'm looking over some equations for the output of a flyback transformer (essentially the same as for a buck-boost converter) and I notice that as long as the flyback operates in the continuous mode, the inductance doesn't enter into the equation. Of course since no inductor is ideal, there must...
The equation widely used to calculate the force on a projectile in an electromagnetic launcher, more specifically a railgun, is:
F = 0.5 * L' * I^2
where:
--> F is the force in Newtons
--> L-prime is the inductance gradient of the rails in henries/meter (H/m)
--> and I is the current...
I just have some confusion about whether or not self-inductance will occur in an AC generator.
The current is alternating in both direction and magnitude rapidly when it is generated and this will in turn cause a changing magnetic field around the conductor. This magnetic field will then...
Homework Statement
A inductor that has a resistance of 80 k-Ohms is connected to an ideal battery of 84V. 0.8 milliseconds after the switch is thrown the current in the circuit is .5355 mA. Calculate the Inductance. answer in units of H.
Homework Equations
V = L(I/t)?
The Attempt...
Hi Friends, :smile:
Two particularly abstract queries have surfaced in my mind (this seems to be a recurring problem with me! ) :biggrin:
CASE 1 :- Infinite Inductance
Let us consider an 'ideal' solenoid coil (zero resistance, pure inductance). It is connected to an AC supply of say...
The images tell it all. Please help someone.
http://image.cramster.com/answer-board/image/200941884006337564080009162509346.jpg
on this diagram, the expression IL(t) should read I(t).
http://image.cramster.com/answer-board/image/2009418845296337564112974787505740.jpg
If there is a circuit consists of a long thin conducting shell of radius a and a parallel return
wire of radius b on axis inside. If the current is assumed distributed uniformly
throughout the cross section of the wire, must we calculate mutual inductance?
Homework Statement
What inductance must be used with a 4.0 µF capacitor to produce a frequency of 10 kHz, which is near the middle of the audible range of frequencies?
Homework Equations
w = 2pi*f/C=1/(sqrt(T*C)) --->angular fequency
T= 1/f
The Attempt at a Solution
T= 2pi/w...
Hi, I am en electrical engineering grad student and I have to solve an equation to calculate the mutual inductance between an antenna and a micro-inductor. I think it is a Bessel equations but I don't know how to solve.
M(a,b,d)=(1.45x10^-8)*integral(J1(1.36x)*J1(0.735x)*exp(-x-13.6))dx...
Homework Statement
Hey guys.
So, I have the next system in the pic.
It's on the xy plan. the poll moves from left to right with a constant velocity. B=B0*x in z direction and the question is to find the current that goes through the poll.
I've also uploaded what I did but I'm a little...