What is Ac circuit: Definition and 197 Discussions

A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The reverse operation is performed by the inverter.
The process is known as rectification, since it "straightens" the direction of current. Physically, rectifiers take a number of forms, including vacuum tube diodes, wet chemical cells, mercury-arc valves, stacks of copper and selenium oxide plates, semiconductor diodes, silicon-controlled rectifiers and other silicon-based semiconductor switches. Historically, even synchronous electromechanical switches and motors have been used. Early radio receivers, called crystal radios, used a "cat's whisker" of fine wire pressing on a crystal of galena (lead sulfide) to serve as a point-contact rectifier or "crystal detector".
Rectifiers have many uses, but are often found serving as components of DC power supplies and high-voltage direct current power transmission systems. Rectification may serve in roles other than to generate direct current for use as a source of power. As noted, detectors of radio signals serve as rectifiers. In gas heating systems flame rectification is used to detect presence of a flame.
Depending on the type of alternating current supply and the arrangement of the rectifier circuit, the output voltage may require additional smoothing to produce a uniform steady voltage. Many applications of rectifiers, such as power supplies for radio, television and computer equipment, require a steady constant DC voltage (as would be produced by a battery). In these applications the output of the rectifier is smoothed by an electronic filter, which may be a capacitor, choke, or set of capacitors, chokes and resistors, possibly followed by a voltage regulator to produce a steady voltage.
More complex circuitry that performs the opposite function, that is converting DC to AC, is called an inverter.

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  1. K

    Question regarding the output for AC circuit with capacitors

    Homework Statement Both diodes are ideal. Answers: (a) Vi (b) -Vi (c) -2Vi (d) none of the above Homework Equations Q=CV The Attempt at a Solution 1. For t=0 to Pi: Cap1 and Cap2 are in series and hence Q1=Q2, therefore Vc1 = Vc2. From this we get Vi = Vc1 + Vc2, hence Vc1 =Vc2 = Vi/2. 2...
  2. A

    Excess Energy Saving from a constant energy source.

    Hello everyone. So i live in Lebanon, and since a long time now we have constant power cuts, almost half the day each day. For that the Lebanese made up a system in which each neighborhood has power generators providing electricity to the residents when the power is out. Usually the owners of...
  3. YellowBelliedMarmot

    Engineering Finding the Current Source of an RLC AC Circuit

    Homework Statement Homework Equations V=IZ[/B] Zc = 1/(-jwc) Zl = jwc w = 2(pi)*f The Attempt at a Solution I'm teaching myself circuit analysis, and it's been rough. Ultimately, I been able to mostly figure everything out, but I've ran into a wall with AC. The main problem I am having...
  4. I

    "AC Circuit Analysis - Find i1(t) & i2(t)

    Homework Statement Find the currents through ##R_3, i_1(t)## and ##R_2, i_2(t)##. I attached a diagram of the circuit (diagram.pdf). In the original diagram the currents I'm trying to find is marked going top to bottom, there's also no directions on the voltages in the original diagram but...
  5. P

    What exactly does the capacitor do in a Tesla coil?

    In all tutorials I have read on tesla coils, they have said to use a capacitor spark-gap configuration, to create a tank circuit. I want to know exactly what this means, and what is its purpose. I am not going to build a Tesla coil, I am nearly just interested in the science of it.
  6. P

    Can you use a tank circuit to produce an AC circuit?

    Since the resonant frequency of a tank circuit, is completely adjustable, and controlled by the value inductor and capacitor you use, I was wondering if it had any other uses, other than increasing its impedance at its resonant frequency. Can if be used to produce ac signals of its resonant...
  7. ReidMerrill

    Capacitor Peak Current and Voltage in an AC Circuit

    Homework Statement A capacitor has a peak current of 240 μA when the peak voltage at 250 kHz is 2.7 V . Part A What is the capacitance? Part B If the peak voltage is held constant, what is the peak current at 500 kHzHomework Equations Xc=1/wC Vc=IcXc The Attempt at a Solution I rearranged...
  8. G

    Engineering Current phase angle difference (AC circuit)

    Homework Statement Three receivers, with complex impedance \underline{Z_1}=(125+j375)\Omega,\underline{Z_2}=(700+j100)\Omega,\underline{Z_3}=(500-j500)\Omega, and two sinusoidal current generators of effective values I_{g2}=40mA and unknown I_{g1} are connected. When the switch is open...
  9. I

    Energy of Inductors in AC Circuit

    Hello, In my textbook, it says that if we have a pure inductor connected to an AC source, the average power is zero. It explains that this is because the energy is used to create a magnetic field for the inductor and then it is extracted to the AC source. So how is it possible for the...
  10. Titan97

    Classical Book for learning AC circuit analysis

    I haven't used any book for AC circuit analysis yet. I have learned the basics of phasor diagrams which my teacher taught in the class (We were only taught series combination of LCR circuits). Can anyone suggest a book to learn more about circuit analysis (like source transformations, Norton's...
  11. Titan97

    Phasor algebra in AC circuit analysis

    Homework Statement Find the peak value of current through the AC source of the following L-C-R circuit, if peak voltage is ##V_0## and angular frequency is ##\omega_0##. Homework Equations I have learned Vector algebra and calculus (single variable). I was taught how to use phasor diagrams...
  12. T

    Engineering Find Frequency for Zero Reactance in AC Circuit

    The question is: The voltage source in the above circuit is a sinusoidal AC source with constant amplitude and constant phase shift but an adjustable frequency. Calculate the frequency ω at which the phasor current I...
  13. R

    Engineering Instantaneous current value in AC circuit

    Homework Statement A sinusoidal supply defined by ## v(t)= 325.27 sin(314.16t+\frac{\pi}{6}) ## is connected across a coil of resistance 25Ω and inductance of 0.5 H. The instantaneous value of the current at 2.968ms is 13.13 mA 21.6 mA 87.8mA 13.8mA Homework Equations ## i(t) = \frac{v(t)}{Z}...
  14. R

    Finding complex power in AC circuit

    In a branch I have to find complex power which is having current 19.41<-37.3 A and impedance 4+j3 Ω What I used is i2z and I was getting 1489.85 - j1152.74 W. This is wrong but I don't know how because by this site the answer was different...
  15. cnh1995

    Creating a GUI for AC Circuit Analysis with Intel Galileo and Arduino

    I have completed a small project of ac circuit analysis on intel galileo in arduino. I want to make a GUI now. How should I proceed? I know C and a little C++.
  16. genxium

    How does surface capacitive touchscreen work in detail?

    It's pretty easy to find the "working principle" of surface capacitive touchscreen like http://www.elotouch.com/Technologies/SurfaceCapacitive/howitworks.asp Roughly speaking, I know that A surface capacitive touchscreen has a conductive layer to which some electrodes are attached The...
  17. R

    Engineering Instantaneous Current in single phase circuit

    Homework Statement SOURCE: v(t) = (311)cos(314t) [v] IN SERIES WITH: R = (0.3) [Ω] L = j(0.7) [Ω] "load" = 2.5 + j(1.0) [Ω]Homework Equations Find the instantaneous current, and the phasor current. The Attempt at a Solution (1.) I first found the frequency of the source: (314) / (2*pi) ≈ 50...
  18. toforfiltum

    Mean power dissipated in resistor in ac circuit

    Homework Statement Homework EquationsThe Attempt at a Solution I am surprised that this question came up, I haven't learned ac circuits yet. I don't know how to solve this. I just added both values and current and divide it by two, which gives me 1.5A, since I thought it's the average but I'm...
  19. M

    AC direction change - how does electricity flow?

    If drift velocity of electrons changes in AC, how does electricity flow through a circuit to then lose potential energy to the devices in the circuit? Also considering the change in direction, does that mean that the live wire and neutral wire also switch roles in AC mains? I am very confused...
  20. V

    Calculating half power frequency/cutoff frequency

    Homework Statement *(Problems attached as images)* For first problem: ##\cfrac{|V_2|}{|V_1|} = \cfrac{1}{\sqrt{4+(\omega RC)^2}}## For second problem: ##\cfrac{|V_2|}{|V_1|} = \cfrac{\sqrt{1+(\omega RC)^2}}{\sqrt{4 + (\omega RC)^2}}## I have to calculate half power frequency for both...
  21. M

    Engineering Calculating Voltage Source in AC Circuit

    Hello, I'm currently working on a problem involving the calculation of an unknown voltage source of a circuit containing a resistor, inductor and load in series. Unfortunately, the problem sheet does not give an answer at the end, so I am unsure as to whether my approach is correct -- hence...
  22. B3NR4Y

    Power in an AC Circuit Problem

    Homework Statement The circuit in operates at 60 Hz with Emax = 170 V, and R = 4.5Ω . How much energy is dissipated in the resistor in 0.75 s? Homework Equations P = VI For a circuit like mine with only a power source and resistor, the current and voltage are in phase, so V = E max sin (ωt)...
  23. NoSniping

    E&M: AC Circuit Light Bulb

    Homework Statement How large an inductance should be connected in series with a 120 volt (rms), 60 watt light bulb if it is to operate normally when the combination is connected across a 240 volt, 60 Hz line? (First determine the inductive reactance required. You may neglect the resistance of...
  24. B

    Need help proving an equation for power loss in a dielectric

    Homework Statement 2. Homework Equations [/B] I am trying to prove the equation $$ \frac{\bar{P}}{V}=\frac{1}{2}E_0^2\sigma_{AC} $$ which can be rewritten as $$ \begin{align} \frac{\bar{P}}{V} &= \frac{1}{2}E_0^2\sigma_{AC}\\ &=\frac{1}{2}E_0^2\ \omega\ \epsilon_0\ \epsilon^{''}_r\\...
  25. J

    What Are the Best AC Power Sources for Lab Use?

    Hi. I'm joining this forum to ask about some equipment I need. At the community college where I teach, we do a lab in freshman physics where students measure the input to and output from a transformer. My AC sources are reaching the end of their lives, so I'm looking for replacements. As far...
  26. E

    Engineering Finding the voltage in this AC circuit

    Homework Statement Homework Equations KVL at that loop The Attempt at a Solution I can easily solve all the individual current and voltages in this circuit using Mesh analysis and Gaussian Elimination. But how do I get Vx? I can simply add the voltages of the two 10uF capacitors if they are...
  27. M

    Engineering How can I find Voltage V in an AC circuit using loop rules?

    Homework Statement Need to find Voltage V. I know that I need to first solve for the currents, have tried using loop rules, not having much luck. Homework Equations Just would like to know how to approach, and solve, this problem. ME and circuits has never been my friend, thanks! The...
  28. S

    Phase Difference between Voltage and Current

    Homework Statement The circuit above has a 29 resistor and a 11.1 mH inductor. Calculate the theoretical phase difference between the current CPA and voltage VPB if the circuit is driven by a sinusoidal voltage source with a peak amplitude of 3.5 V at the following frequencies: 20 Hz 420 Hz...
  29. 2

    Transforming DC to AC: The Role of Inductors and Capacitors in RLC Circuits

    I have only just found out about inductors, and am trying to figure out how a circuit with an inductor and a capacitor could change dc current to ac current. With the set up of the circuit, would it suffice just to have the dc supply with a 'gate' that stops/allows through the dc current with a...
  30. A

    How to find supply frequency of an AC circuit

    Homework Statement [/B] Parallel circuit consists of 100ohm resistor with 0.4A current, a 0.47uf capacitor with 0.177A current. Both connected across an AC supply, determineHomework Equations [/B] The supply voltage The supply frequency Current drawn from supply Power factor of the circuit The...
  31. H

    Engineering AC circuit analysis -- mesh and nodal

    Homework Statement Determine, using the values given in TABLE A, the current I in the circuit of FIGURE 2 by: (a) mesh analysis (b) nodal analysis. Any help verify for part (a)? And to help me get started with (b) as V3 is driving me nuts. Homework EquationsThe Attempt at a Solution For (a)...
  32. K

    Engineering Solving an AC Circuit Problem with R, L, C Values

    Homework Statement http://i.imgur.com/HTGycr8.png?1 f = 248 Hz\Rightarrow \omega = 1558.23r/s\\ L = 34 mH\\R = 7\Omega\\\alpha = -6°\\C=? Alpha is the angle between current and voltage (V - I). X_L=\omega\times L=1558.23 * 34 * 10^-3 = 52.9798 \Omega Homework Equations \arctan{\frac{R}{X}} =...
  33. Captain1024

    Obtain Expression For Voltage Across Capacitor

    Homework Statement A voltage source given by ##v_s(t)=25cos(2\pi\times10^3t-30^\circ)## is connected to a series RC load. If R = 1MOhm and C = 200pF, obtain an expression for ##v_c(t)##, the voltage across the capacitor. Answer known to be: ##v_c(t)=15.57cos(2\pi\times10^3t-81.5^\circ)##...
  34. 159753x

    Calculating voltage division for an AC circuit?

    Homework Statement A series RL circuit is connected to a 110-V ac source. If the voltage across the resistor is 85 V, find the voltage across the inductor. Homework Equations V = IR The Attempt at a Solution How does one go about solving this? My intuition tells me that KVL must be...
  35. docsxp

    Help with AC Circuit containing a motor

    Hello, this is not a homework question, but is a past year exam question which I'm stumped at. Any help will be appreciated. 1. Homework Statement We're designing a current reduction system for an AC motor which is modeled as an inductor ##L##in series with a resistor ##R##. This motor is...
  36. E

    RLC Circuit Frequencies Help

    Homework Statement In each of the four circuits shown, an AC input voltage, ##V_0 cos(\omega t)## is applied on the left and the output voltage is measured on the right. Treat the input frequency as a...
  37. B

    Engineering AC Circuit with Dependent Voltage and Current Sources

    I have trouble solving the following problem. Am I supposed to start by doing nodal analysis on the loop on the right. Can someone give me a start. Thanks...
  38. Rugile

    AC circuit - voltage drop and resonance

    Homework Statement An AC voltmeter connected to the nodes A and B shows the same value as when connected to the nodes A and D (refer to attachment). What is the inductance of the inductor? What value does the voltmeter show? The inductor is ideal. U = 70sin(314t) V, C = 80 μF, R = 500 Ω...
  39. AakashPandita

    To find the current through an inductance in an AC circuit.

    Homework Statement An inductance is connected across an AC current generator. Homework Equations v= L di/dt = Vsinωt The Attempt at a Solution i=∫di= V/L ∫sinωt dt= -V/ωL cosωt This is what is written in my book. But wouldn't there be a constant at the end of the indefinite...
  40. P

    Thevenin equivalent for an AC circuit

    Homework Statement I have the network attached below. I need to find the open circuit voltage and short circuit current between A and B and then use these to find the Thevenin equivalent for the circuit. The Thevenin equivalent voltage is of the form VTsinwt and the equivalent impedance is...
  41. dwn

    Engineering Thevenin AC Circuit Homework: Solve & Analyze Results

    Homework Statement Image Attached Homework Equations Thevenin, Series, Parallel The Attempt at a Solution j10(12-j34) / (j10+12-j34) = (340 + 120j) / (12/j24) 1.67 + j13.3 or 13.44∠82.4° Now why can't I just use this equivalent resistance and multiply by the current source (22∠30°)...
  42. M

    Engineering AC circuit, voltage expressed by time

    Homework Statement A voltage source e(t) = 50 sin(2000t + 30°) V supplies the current i(t) = 0.5 cos(2000t) A in a circuit. Find the impedance in the circuit, in both polar and rectangular form. Is the circuit inductive or capacitive? Homework Equations The Attempt at a Solution...
  43. M

    Engineering How to Find Power in an RLC Circuit

    Homework Statement A1 = 5A, A2 = 4A, A3 = 3A. V = 120V a) Given the circuit above, find A4 b) Find the angle between E and IT. Draw a diagrammatic (?) and find the power in the circuit. c) Find the values of R, L and C. Homework Equations The Attempt at a Solution...
  44. M

    A capacitor in an AC circuit. What is the amplitude of the current?

    A capacitor in an AC circuit. What is the amplitude of the current?? Homework Statement I really do not know how to approach this problem. What confuses me is that when calculating the % error I'm suppose to have a theoretical or accepted value and a measured value. So how do I determine...
  45. D

    Engineering Where Did I Go Wrong? Solving Admittance in a Basic AC Circuit

    Okay so I have been working on a problem for practice for an exam and this one question is really pissing me off. I can't find what I am doing wrong and I've redone it about five times. The question is asking for the admittance of the circuit and the answer is given as 2.29 S at an angle of...
  46. D

    Effect of a capacitor on an AC circuit

    Hi! I'm in a place where electricity goes out frequently; as a result I got a UPS which is powering my computer the total power input of which is less than 200W. The UPS is 300W or 600VA. The transfer time (time to switch from AC mode to battery mode) of the UPS is around 4 ms; but in that...
  47. C

    What is the average power if the resistance R is doubled in an AC circuit?

    Homework Statement The average power dissipated by a resistor is 4.0 W. What is the average power if the resistance R is doubled? Homework Equations P_{rms}=I_{rms}^2R=I_{rms}V_{rms}=\frac{V_{rms}^2}{R} The Attempt at a Solution I am told the answer is 2.0 W. But here's what I am confused...
  48. gfd43tg

    Engineering Nodal Analysis with AC circuit

    Homework Statement Apply nodal analysis in the phasor domain to determine ix(t) in the circuit below. Homework Equations The Attempt at a Solution This is super confusing to calculate in the phasor domain, I was just wondering if anyone could check my calculations and see if they...
  49. V

    Engineering Calculating Maximum Average Power of AC Circuit

    Homework Statement Homework Equations The Attempt at a Solution The text in the black box looks wrong to me. The method below is how I would do it. Why is it wrong? $$To\quad maximize\quad power,\quad \overrightarrow { Z_{ L } } =\overrightarrow { { { Z }_{ th } }^{ * } } \\ \\...
  50. D

    Engineering Analyzing AC Circuits: Finding Current and Thevenin Impedance

    Here I have a problem I am dealing with. I answered the question and have it shown on the picture but I would like a double check on it as I think I am getting wrong values. The circuit is shown at the top of the page. If you can't see the values are 10 ohms for the resistor, 3.2 mF for the...
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