What is Rc circuits: Definition and 88 Discussions
A resistor–capacitor circuit (RC circuit), or RC filter or RC network, is an electric circuit composed of resistors and capacitors. It may be driven by a voltage or current source and these will produce different responses. A first order RC circuit is composed of one resistor and one capacitor and is the simplest type of RC circuit.
RC circuits can be used to filter a signal by blocking certain frequencies and passing others. The two most common RC filters are the high-pass filters and low-pass filters; band-pass filters and band-stop filters usually require RLC filters, though crude ones can be made with RC filters.
I thought that if the slope of the T versus R graph is 4.00μF, then the capacitance would be 4.00μF but it says that's wrong. I know I'm doing something wrong but I'm not sure how to approach this problem. Can someone help?
Hello, this is my working. My professor did not give any answer key, and thus can I check if I approach the question correctly, and also check if my answer is correct at the same time.
When t < 0, capacitor acts as open circuit,
$$V(0-) = V(0+) = 9V$$
When t = infinity,
$$V( ∞) = 5V$$ (because...
Now that currents don't flow past the interior of capacitors at any time (charging/discharging etc), currents should be functions of a spatial coordinate, i(x), in that i(x) is non zero in wires and 0 in capacitors. But in circuits usually currents are assumed constant in the same branch. What...
Hi all.
I have another exam question that I am not so sure about. I've solved similar problems in textbooks but I have a feeling once again that the correct way to solve this problem is much simpler and eluding me.
Especially because my answer to a) is already the solution to c) and d) (I did...
Homework Statement
So I am solving a 555 timer questions, and there is a resistor that is grounded on both terminals at one point. My question is what does this do to the resistor?
Homework Equations
Vc(t) = A + Be^(-t/(R*C))
The Attempt at a Solution
I know that if you ground one terminal...
Homework Statement
So I need to find the equivalent resistance for the following RC circuit to calculate the time constant, but I got stuck in terms of finding out the equivalent resistance.
Homework Equations
V = IR
The Attempt at a Solution
So the thing I am not sure on is how do you...
Homework Statement
RC circuit, with a resistor, capacitor and a switch with
ΔVC =80V R=1.5MΩ C=22μF
The switch is initially open. The switch is closed at t=0
(a) What is the charge in the capacitor when the current is 33μA
(b) How times does it take for the current to reach 33μA...
Homework Statement
Suppose a 120 micro-farad capacitor from a camera flash unit retains voltage of 210 V when an unwary student removes it from the camera. If the student accidentally touches the two terminals with his hands, and if the resistance of his body between his hands is 1.8...
Homework Statement
Homework Equations
##q = CE(1 - e^{-t/RC})##The Attempt at a Solution
I assumed that, since the problem specifies that sufficient time has passed, it meant to say that enough time passed. thus making the exponential term in the equation go down to 0, and the charge in the...
I have a circuit which it looks like this.
We need to write the general RC equation.Can I reduce this circuit to like ##R_{eq}## and ##C_{eq}## then solve it ?
This is not a homework question.Just need theoretical approach
Homework Statement
[/B]
My question is regarding part C of the question.
Homework Equations
V = IR
V(t) = V(1-e^(-t/tau))
The Attempt at a Solution
My idea is to use Kirchoff's Voltage Law and find the voltage of the capacitor as a function of time, then since the voltage across capacitor is...
Homework Statement
1. (35 pts) You have a coop job helping to test a capacitor energy storage system. There is a rather large capacitor with capacitance, C = 2.02F. It is charged to a potential V = 602.V with the polarity of the capacitor as shown. The large, solid line on the right of the R–C...
Hi, I was wondering on how to implement a sinewave oscillator with a variabke frequency from 20hz to 20khz.
What types of circuits are there to do this and what sort of parameters would affect the frequency range?
Thanks
Homework Statement
For my lab class my professor wants us to graph the theoretical amplitude of the output from a low-pass filter vs. frequency. I have the resistance and capacitance that I chose for the RC circuit and a V(in). Is there an equation that I should be able to use to relate these...
Homework Statement
I posted the entire question, but I am only conserned with part B.
There was a circuit drawing on there but it is irrelevant for this part of the problem. One can solve it without knowing the circuit drawing.
Homework Equations
The application for Kirchoff's Voltage Law...
Homework Statement
This isn't so much of a problem itself but I found it interesting that on the All About Circuits website, two of the questions give a phase angle for impedance as opposite the angle of current. I understand the current is 90 degrees out of phase with voltage in both RL and RC...
Homework Statement
A parallel combination of 0.1M Ω resistor and a 10 μF capacitor is connected across a 1.5 V source of negligible resistance. The time (in seconds) required for the capacitor to get charged upto 0.75 V is approximately
(A) ∞
(B) ln 2
(C) log 2
(D) Zero
Homework Equations...
Problem is in the picture below.
The problem is already solved, but I am confused as to why C(dv/dt) is positive and not negative, since the current is coming out of the capacitor and towards the point v(t), which is not away from v(t) like the solution shows. But if I solve the problem with...
Homework Statement .
[/B]
This is problem 7.45 in Fundamental of Electric Circuit 5th edition.
2. Homework Equations
First off, I want to go ahead and say that I don't need the solution I already solved it.
I went ahead and used Nodal analysis when Vs = 30. I placed a node voltage right...
Homework Statement
Question is attached below
Homework Equations
v(t) =v(infinity) + [v(t0)-v(infinity)]e^[-(t-t0)]
The Attempt at a Solution
For t<0, you get the circuit where it is only Rt, R, and C, but in dc circuits, the capacitor is an open circuit, does this mean v(t0) =0?
For t>0 the...
Homework Statement
Hi, I already asked a question close to this, but now I have different conditions.
This is the circuit
C_1 = C_2 \\
R_1= R_2
The current is an AC , and I would like to know the voltage at R_1 and at R_2
I made some progress but I do not really know hot to continue...
Help understanding rc circuits?
so I know the voltage drop must be 8 v through the r1 resistor because of the 12 v charge on the capacitor. 8= r1*i and now I set up another equation 12= r2*i= 15*i and when I solve for the current I get 4/5 a but my textbook lists 3 amps as correct. Can you...
I understand that the voltage phasor for a resistor is in phase with the current phasor in a simple ac circuit consisting of only an AC voltage source and the resistor.
I understand that the voltage phasor for a capacitor is pi/2 radians behind the current phasor for an AC circuit consisting...
I understand that the voltage phasor for a resistor is in phase with the current phasor in a simple ac circuit consisting of only an AC voltage source and the resistor.
I understand that the voltage phasor for a capacitor is pi/2 radians behind the current phasor for an AC circuit consisting...
Hi. When trying to derive the equation for voltage across a discharging capacitor in series with a resistor using Kirchhoff's laws, I got stuck. My attempt was that the voltage gain across the capacitor should equal the voltage drop across the resistor, therefore q(t)/C = i(t)*R, or q(t) -...
These are 2 stand alone problems, however the answers disagree with one another and I am trying to reconcile their differences. Any insight would be appreciated! :)
The answer is C. The answer provided with this question is that "there is no dependence on resistance of any kind".
However the...
Homework Statement
Determine the voltage drop across the resistor when the capacitor has been discharging for 10μs.
Capacitance=400 pico farad and is charged to 10v through a 50kΩ resistor.
Homework Equations
Vr= V*e -t/CR
The Attempt at a Solution Vr = V-Vc at the instant of 10μs...
Homework Statement
Determine the current flowing when the capacitor has been discharging for 5μs
Capacitance=400 pico farads which is charged to 10v through a 50kΩ resistor.
Homework Equations
Vc = ve-t/CR
The Attempt at a Solution So Vc =Ve -t/CR
-t/CR =...
Dear all,
I have problem to find the differential equation for my circuit shown in the attached picture.
For input I have a current source, and the output is the voltage U (the voltage between the first and the ground node). I need the ODE to find the mathematical response of the system...
Hey PF!
I have a test tomorrow and some of the material is on the basics of RL and RC circuits set up as high pass or low pass filters. Does a High pass filter bode plot look the same whether it's RC and RL? Same with a low pass? Can anybody to an online resource of what bode plots look like...
Homework Statement
Plot I_r vs. time and Q_c vs. time starting from when the switch is moved from its lower position to its upper position. Label both axes with numbers and units. Show three time constants. Assume that the capacitor is initially uncharged. After the circuit reaches its...
Homework Statement
A simple type of blinking light circuit can be constructed using a neon lamp. The circuit has a 4.0uF capacitor in parallel with a neon lamp. When the voltage is low in the RC portion of the circuit, the lamp does not conduct electricity. Therefore, it is effectively not...
Homework Statement
"A capacitor is being charged from a battery and through a resistor of 20kΩ. It is observed that the voltage on the capacitor rises from 10% of its final value to 90%, in 15 seconds. Calculate the capacitor's capacitance.
t = 15s
R = 20kΩ
Vi = 10% of max
Vf = 90% of max...
Hello,
At the moment, I am writing the theory portion of my lab report. In the RC circuit, will the electric potential across the capacitor be at the same electric potential as the battery? Or will it depend on the voltage drop across the intermediate resistor?
Homework Statement
Find v(t) after t=0, when the switch moves up
need to know if i did this right.. V(C1)=V(C2)=10V (this is same for t=0- and 0+)
V(infinity)=0V (no voltage source)
T=RC=100k(ohm)*(4uF)=0.4 sec. (i got the 4uF by putting the 2 caps. in parallel with each other, because they...
Homework Statement
For the circuit below, the switch has been closed for a period of time long enough for steady state conditions to have been reached.
a: Determine the time constant before the switch is opened
b: Determine the time constant after the switch is closed
c: Determine the...
[b]1. You are investigating how energy is transferred in circuits with batteries, resistors, and a capacitor. First you take an uncharged capacitor and connect it in a simple series circuit with a resistor and a battery. You wait for the circuit to reach a steady state. After a steady state is...
RC circuits -- questions about the solution
Homework Statement
First of all , greetings from Peru and thank you to all the people who help another people here,taht's awesome , please help me with this guys... Here's the statement
The solution is
My questions:
ok my question is about the...
Homework Statement
Given the drawing, calculate the current going through the 2Ω Resistor and then calculate the difference in electric potential from point a to b.
Homework Equations
V = IR
juction rule:
ƩI = 0 = Iin - Iout
ƩV = 0
The Attempt at a Solution
Well, I attempted to draw all the...
Homework Statement
In the circuit shown in the following figure(Figure 1) the capacitor has capacitance 20 microF and is initially uncharged. The resistor R_0 has resistance 12 Ohms . An emf of 90.0V is added in series with the capacitor and the resistor. The emf is placed between the...
Homework Statement
Relevant infor
V(out) stands for the voltage divider I believe
The Attempt at a Solution
I am just going to get the equation first.
For the first part, applying the loop rule I got
12 - 10^5q' - 10^7 q = 0 with q(0) = 0. Solving I get
Q =...
Homework Statement
Circuit is at this link: http://www.colorado.edu/physics/phys1120/phys1120_sp08/hws/capa8_figs/gian1946.gif
1. What is the potential at point a with S open (let V=0 at the negative terminal of the source, and assume it's a long time after the circuit was connected to the...
Homework Statement
You need to modify a simple charging RC circuit (power supply, resistor, and capacitor in series) to maintain the same maximum current but lower the the time constant and make it charge faster. Which of the following will accomplish it?
A) Same R, lower C.
B) Same R...
Homework Statement
A circuit includes a spark gap that connects to the ground. The width of the gap is adjusted so that the capacitor discharges to the ground each time the voltage reaches 99% of the maximum.
(The circuit is basically a simple series circuit with an 80v power supply...
Homework Statement
In a problem I have a circuit that I have not set up to know what happens as far as voltages across my battery(4v), two equal resistors and a capacitor.
Homework Equations
The Attempt at a Solution
Because i have not seen a circuit like this I am thinking that...
Homework Statement
What causes integration of V_{in} within an RC circuit?Homework Equations
Z= R + X_C
= R - j/(ωC)
Z is the impedance of the circuit, j=(-1)^.5, ω is angular frequency, and C is the capacitance.
The Attempt at a Solution
I think integration is the capacitor's way of...
Homework Statement
S1 switch - always close.
S2 switch is closed, until the capacitor voltage reaches 2V.
given: R,C,V values.
V0 = 0V.
Need to find Vout while S1+S2 are closed and until S2 opens.Homework Equations
Vc(t) = (Vi - Vf)*(exp -t/TAU) + VfThe Attempt at a Solution
I have found the...
Trying to understand the power network and synchronous machines, led me to the fact that I am not sure about the basics.
The terms the generator is delivering or consuming reacting power made me halt.
So I went back to my old course(which I allegedly passed) where the reactive power is...
Homework Statement
Maximum current:
I max = 4.62 * 10^-4 A
Time constant of circuit:
T = 3.9 secondsHomework Equations
T= RC
The Attempt at a Solution
I'm trying to find the current after 1 time constant. Seems simple enough, the current changes by 63%. So (Imax)-(Imax * 0.63) or...