Lc Definition and 167 Threads

Alright, I have an LC circuit. Using conservation of energy, I get \frac{dI}{dt}= \frac{-q}{CL} which gives \frac{d^2q}{dt^2}= \frac{-q}{CL}, therefore, q=q_o sin(\omega t +\phi), where \omega= \frac{1}{\sqrt {LC}}, giving q=q_o cos(\omega t) which implies I= -q_o \omega sin(\omega t). Now...

Homework Statement A constant voltage at a frequency of 1MHz is maintained across a circuit consisting of an inductor in series with a variable capacitor. When the capacitor is reduced from 300pF to 284pF, the current is 0.707 of its maximum value. Find (i) the inductance and the resistance...

I recently read that a 1/4 wave resonator is equivalent to a series lc circuit but with a much higher q. In a typical resonant LC series circuit voltage magnifications exists, does the same thing occur in a 1/4 resonator since it is equivalent to a series LC circuit? Thanks in advance!

If a lc resonant tank circuit is disconnected from power how do you determine the length of time it will oscillate. L=1 henry, 500 ohms C=50pf Fres=22,507 hz

LC circut: Charge on a capacitor at a given time Homework Statement I don’t have a pic but a simple loop circuit is constructes with 2 capacitors c1 and c2 in series, after the capacitors in an inductor also in series, and the wire continues back into c1. The values for the capacitors...

I was reading a very old article this morning about electrical theory, it was talking about the flow of current in a tank circuit otherwise known as a tuned cct. (parallel LC cct). A strange and disturbing thought struck me. I know *how* a tank cct oscillates. but I don't have the foggiest...

Current increases up to a certain point, and then decreases until it reaches zero. Then it does the same thing in the other direction. Here's my problem. Without the inductor, the current would not increase over time: it would decay until the two plates had equal charge. With the inductor, I...

In an oscillating LC circuit, L=25 mH and C=7.8 x10^-6 F. At time t=0 the current is 9.2 mA, the charge on the capacitor is 3.8 x 10^-6 C, and the capacitor is charging. What is the total energy in the circuit? I know I just need to do Ub+Ue=U, but here is my question. Are L and C constant...

Hi all I am searching for theory on LC oscillations ... but can't find something good ... Can anyone suggest me some page?

Homework Statement An LC circuit is shown in the figure below. the 33 pF capacitor is initially charged by the 6V battery when S is at position a. Then S is thrown to position b so that the capacitor is shorted across the 15 mH Inductor. Homework Equations w= 1/sqrt(LC) XL = wL...

Homework Statement Suppose we have a circuit with the inductor, uncharged capacitor, ideal battery with emf E all in series. At t=0, the circuit is switched on. The following takes place sequentially: 1. Current at t=0 is max. Battery charges capacitor, current decreases. 2. inductor...

I'm trying to understand why the voltage in a series LC resonant circuit exponentially rises? Can anyone explain exactly what happens that creates the effect? I've been wonding if it the distributed capacitance of L becomes a voltage multiplier, or if it is a voltage wave reflection...

A series LC circuit at resonance has a higher total voltage than the applied voltage due to voltage magnification. If a diode were inserted between L and C it would prevent the back and forth oscillation of energy, But would it prevent voltage magnification if the circuit were driven at...

I am trying to figure out what the voltage across each component will be. In the cirucit above resonance occurs between inductor L1 (5 Henries) and Capacitor C1 (10nF) The other inductor (L2) is 10 Henries and the circuit's resistance is 1,000 Ohms. Here's my attempt at figuring the voltage...

Homework Statement An LC circuit constructed of a 1 microF capacitor and a 1 microH inductor is set in oscillation so that the charge on the capacitor is 1.0 microC at t = 0 and 2.0 microC at t = 1.57 x 10^-6 s. What is the charge on the capacitor at t = 1.0 s? Homework Equations Q(t) =...

Homework Statement There's an LC circuit that's made of an 31 mH inductor and a planar capacitator. The surface of the plate is 20cm^2 and the distance between the plates is 1 cm. What is the electrical permittivity of the insulator between the plates , if the peak current is 0,2mA and the...

Homework Statement All the electric energy in a capacitor is converted to magnetic energy in 1.61 micro seconds. What is the period of oscillation?Homework Equations I assume Ue = q^2/2c, Ub = -.5 Li^2, w = 1/sqrt(LC) = 2 pi fThe Attempt at a Solution I worked around the equations Ue = q^2/2c...

Homework Statement The first circuit has a capacitor with capacitance c and an inductor with inductance L. In series with this is another capacitor which is connected to the next loop in the circuit. It look something like http://imgur.com/YJDaD.png" Sorry for the crude drawing...

Hey everyone, So I'm working with this simple LC circuit where the capacitor has been charged to some Qmax. I want to derive the relationship for Q(t) (aside from using the book). But I'm stuck. The book's derivation uses kirchhoffs law of voltages around a loop. But it seems to me...

Homework Statement Since I don't have a pic.. I will explain my problem. I have a circuit with 3 terminals x , y and z. Between x - z I have a resistance , say R, Between z - y I have an inductor L and then a capacitor C in series. I apply a square wave input between x and y. Homework...

I wonder if LC curcit radiates energy? Probalby not because according to equations energy is not lost during its vibration. But I heard it was used in very simpe radio receivers. Is it true.

http://img295.imageshack.us/img295/6016/55877904.th.jpg I tried everything to solve this. XL and XC are an inductor and a capacitor (respectively). I start with the idea that there are 50 V on each of them, and that a current of 5 A flows between, and that the generator has no effect, because...

I am unable to relate the Barkhausen criterion for oscillations to sustain to the Ideal LC oscillator with an initial condition. Assume you have a parallel combination of LC(both with Q=infinity) with an initial condition say V volts on capacitor. Mathematically it will oscillate with the...

I have been thinking about a scenario in which I might have a series LC circuit, but where one plate on the parallel-plate capacitor is attached to a spring. How would I model such a scenario, and how would I determine the ideal resonant frequency of the entire system? I have attempted two...

Homework Statement An LC circuit with an inductor of 4 microH is used as tuner for an FM radio. The capacitance required to tune into a radio stations of 100 MHz is most nearly what? Homework Equations w= 2pif = 1/sqrt LC The Attempt at a Solution I plugged in 4 microH into...

Homework Statement In an oscillating LC circuit, L = 2.93 mH and C = 3.21 μF. At t = 0 the charge on the capacitor is zero and the current is 2.14 A. What is the maximum charge (in C) that will appear on the capacitor? Homework Equations I know that for an LC Circuit, the charge q at...

A circuit has a battery(V), Capacitor(C) and Inductor(L) connected in series. At t < 0, the switch is open and the capacitor has an initial charge of -800uC and Io = 0.0Amps.. When the switch is closed at t = 0, I want to know what happens here. I only understand an LC circuit where there is...

Setting up an LC circuit is difficult because I find it hard to make a reliable inductor and do not have the resources to get one. However, if I used an electric motor, which has an induction coil, would that suffice? Or is there something obvious I am missing? Also, if this is feasible, how...

Hello, This is such a great community! I've got some great input from here in the past! I took a bit of a break but I'm back to playing around and trying to learn about electronics and circuits and I wonder if I can pick your wonderful brains again :) Ive learned that a circuit with a...

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...

I'm having problems filtering out certain frequencies from others with a series LC filter. I have a 1.923 Henry DC filter choke inductor set in series with a 0.1 micro Farad capacitor. I send the signal through the inductor to the capacitor and output from the other side of the capacitor. I'm...

"At resonance frequency, the circuit impedance is maximum. It is resistive and its value is given L/Cr..." The book doesn't explain how impedance equals L/Cr, so I'm confused here. How is it derived?

"At resonance frequency, the circuit impedance is maximum. It is resistive and its value is given L/Cr..." The book doesn't explain how impedance equals L/Cr, so I'm confused here. How is it derived? (Can you please show all the steps?) Thanking in advance...

So I have an LC circuit at resonance except the capacitor gets very hot. There is about ~2Amps AC going across it. The setup is: 2x 0.1uF capacitors in parallel ~304uH inductor the ESR of the cap is 0.56ohms and the resistance of the inductor is ~0.7ohms. I was looking for the...

In a series LC ckt, the capacitor charges to the applied voltage V after some time t1secs. Now there is no voltage across the inductor. How can the inductor keep supplying current to the capacitor, when the potential difference across it is zero. The capacitor is charged up to 2V. Why just 2V?

Homework Statement The 300 μF capacitor is initially charged to 100 V, the 1200 μF capacitor is uncharged, and the switches are both open. So the picture is two capapcitor in either side of the circuit. There is a inductor 5.3 H in the middle wire that divide the switches in eaither side of...

Will the frequency of EM waves produced by oscillating current in an LC circuit be the same as the frequency of the current? Thanks!

Homework Statement A variable capacitor with a range from 10 pF to 420 pF is used with a coil to form a variable-frequency LC circuit to tune the input to a radio. (a) What ratio of maximum frequency to minimum frequency that can be obtained with such a capacitor? ANS:__________ (b)...

Why the LC oscillator ckt. is also known as a TANK ckt.?

What size capacitor would you install in a series-tuned LC circuit with a resonant frequency of 2 KHz the circuit will include a 2 mH inductor? This is my question and here is what I got. Just want to know if it is right. 2.52 i do not know how to put the formula in here. can anyone show me...

Homework Statement Hi When you set up an LC (tank) circuit there is oscillation due to charge and discharge of capactor and storage of energy in the inductor. How do you prove that it is simple harmonic? And also how do you prove (mathematically) energy is conserved in an undamped LC...

I thought these were weird similarities between macroscopic electronic circuits and (Bohr) hydrogen model. What do you guys think? . hydrogen self-capacitance (energy level "capacitance") C = 4*pi*eo*br = 5.88798e-21 Farads eo = vacuum permitivity br = Bohr Radius m = electron mass e =...

Consider an ideal LC tank circuit with some initial conditions such that oscillations take place. I am trying to find the amount of power radiated per cycle due to the accelerating charges (I realize that this should come out to be a very small value). Setup and solve the relevant differential...

I have a clearance question. I’m in need of understanding the clearances and tolerances associated with the sliding parts in a sliding bolt fire arm. The moles are really going to hate this. After some time goggling, reading, and with a year of mechanical drafting, I estimated that ANSI RC 8...

At t = 0, Q0 = 18 C and I = 0 in an LC circuit. (a) At the first moment when the energy is shared equally by the inductor and the capacitor, what is the charge on the capacitor?

Homework Statement A radio receiver contains an LC circuit whose natural frequency of oscillation can be adjusted, or tuned, to match the frequency of the incoming radio waves. The adjustment is made by means of a variable capacitor. Suppose that the inductance of the circuit is 11.00 μH. What...

I understand how an LC circuit oscillates and radio waves are a result. I also understand that any light from the electromagnetic spectrum has an electrical and magnetic component. Where does the magnetic component come into play in an LC circuit. Thanks.

A series LC circuit contains a 100 mH inductor, a 36.0 mF capacitor and a 12 V battery. The period of the electromagnetic oscillations in the circuit is 1. 0.0227 s. 2. 1750 s. 3. 105 s. 4. 2.26 s. 5. 0.376 s. f= 1/ 2*π *√L *C L =100mH C= 36uF so,,f = 2.65...

[SOLVED] Finding current in LC circuit Homework Statement A 18.0 \mu {\rm F} capacitor is placed across a 22.5 {\rm V} battery for a few seconds and is then connected across a 12.0 \rm mH inductor that has no appreciable resistance. After connecting the capacitor and inductor together, find...

Homework Statement An LC circuit starts at t=0 with its 2000 microF capacitor at its peak voltage of 14V. At t=35 ms the voltage has dropped to 8.5 V. a) What will be the peak current? b) At what time will the peak current occur? c) What must be the value of the inductor in the circuit?The...