Ac Definition and 1000 Threads

  1. F

    What causes an AC motor to pull locked rotor amps?

    When an alternating current motor first turns on, what causes an alternating current motor to pull locked rotor amps for approximately one second after first turning on as opposed to just pulling the same amount of amps the entire time? What causes the amperage on an AC motor to drop after...
  2. H

    Why is the correct polarity important with AC?

    Hi! I was watching some random videos about electricity on you youtube and then got this question: if AC changes direction constantly (50 times per second) then why is it still important to connect live to live and neutral to neutral in wall outlets? For example some wall outlets have different...
  3. J

    Electrical WIFI 120 volt AC run on 12 volt DC

    I am getting one of those $10 WIFI units from china runs on 120 volt AC and I want it to run off of 12 volt DC car battery I am thinking will need to open up unit and try to figure out what the DC voltage is that is coming from the AC supply unit and then insert a fixed regulator of 12 or 5...
  4. M

    Calculating Vo in an AC Circuit Using Superposition Theorem

    This is the circuit: I try with KVL: But the given answer is 6.66L33.67 Volts. So, I'm confused, any suggestions ?
  5. W

    Theoretical question about an electromagnet in an AC circuit

    This may be a stupid question, but here is what I am asking. Using a very simple circuit, say 120v AC water heating element rated at 1000 watts meaning 120v AC hot leg on 1 terminal and a neutral on the other terminal. That would give 8.3 amps of current, meaning the resistance would be 14.4...
  6. Zahid Iftikhar

    Voltage across R, L and C vs AC Voltage source in RLC Series Circuit

    One property of series resonance circuit is that at resonance, the voltage across circuit elements R,L and C may be larger than the source voltage. I can relate it to vector analogy where component vectors may have larger values than the resultant and the phenomenon is counter-intuitive. This...
  7. Edwina Lee

    Running an AC Mains powered fan at different speeds

    My mother has an alternating current extractor fan plugged into the mains. I want to run it at different speeds. I am thinking of using a light dimmer switch to deliver variable voltage to control the fan speed. (An electrical engineer friend told me that it is possible only if the fan is...
  8. D

    Does an AC Magnetic field induce movement in a DC Magnetic Field?

    Summary: Can a rotating AC Magnetic field induce movement in a static DC Magnetic flux? I'm designing a control panel, and the customer has asked us to reduce the EMC as much as possible; there are no drives, or other noise creating devices, just AC circuits. I thought a good starting point...
  9. J

    Power Loss in Transmission Lines: AC vs DC Comparison Explained with a Model

    Intuitively I fell like AC would lose more power long a long power line than DC. I will use a model to explain my perspective. Let me model a wire as a long straight, non-frictionless tube, about the diameter of a marble, filled with a row of marbles that are each connected to the one next to...
  10. Efeguleroglu

    Why RMS for the average voltage in AC current?

    We write rms formula as $$v_{rms}=\sqrt\frac{\int_a^b[f(x)]^2dx}{|b-a|}$$ I know if we take arithmetic mean average voltage will be 0. So we want all voltage values to be positive. Why don't we do that: $$V_{average}=\frac{\int_a^b\sqrt{[f(x)]^2}dx}{|b-a|}$$ That's first what I did...
  11. F

    Use a MATLAB Workspace to get the unknown values in an AC circuit

    The plot of part b is attached below. I got a warning on part a , I don't know where is my mistake . Please check my work . Part A clc; clear all; %parta f=800; t=0:10e-6:0.005; xc=10^(-6); xl=40e-3; for i=1:(0.005)/(10e-6) w=2*f*pi; zeq=xl*j*w+50; is(i)=2*(1600*t(i)*pi)...
  12. F

    Engineering Draw the magnitude and phase angle of a voltage in this AC circuit

    My solution is attached below. I am not sure if my answer is correct or not , I want to confirm it.
  13. X

    Computing AC voltage in a complex filter

    Problem Statement: Computing AC voltage Relevant Equations: cut off frequency, ac voltage. Hey guys, Amazing to be in this group ! Please find attached the diagram of the problem. E = 10kV at 60Hz, C1 = 60pF and R1 = 1k. I have to compute the ac voltage in reference to ground at point [1]...
  14. P

    How to calculate the voltage induced in a coil by an AC magnetic field?

    So, as it says in the title, I am trying to calculate overall voltage induced in a coreless coil in the cases of it being stationary and moving in an alternating magnetic field. To go more into detail, I would like to create a mathematical model of a coil in an alternating magnetic field that...
  15. F

    Query about the time average of an AC power supply

    Hi there, I have a query about electric power in AC systems. I am Chilean, and over here the power supply is 220 V (rms) at 50 Hz. Some countries use voltages in the range 200-230, but others use 110 V or so, at frequencies of 60 Hz. There is no uniqueness, but all work. My question is...
  16. A

    AC Induction motor startup current

    Friend gave me this task he had back in school to calculate the necessary amperage for a fuse that is put in series with one of the phases for a 3 phase induction motor. I could calculate the working current of the motor from the rated kW and cos voltage/current angle, but I couldn't figure out...
  17. S

    AC Current versus AC Voltage on the Neutral Wire of AC Mains

    Sir how can one explain with the help of an analogy to a grade 10th student the reason behind not getting a shock on touching the neutral wire of the household AC circuit, even though the current flows alternately through live as well as neutral wires.
  18. K

    The Neutrality of NaCl: Comparing H+ and Ac-

    First question: Here they just conclude that NaCl is neither acidic or basic, and that pH is unchanged.Second question: Here I thought that the pH would just be the concentration of HCl, as NaAc is a salt, but in the solution they instead say that H+ will combine with Ac- to form HAc. Why is...
  19. Peter McBride

    AC Single phase stator wiring help

    This stator is out of a Wisconsin VG4D gas motor. Both black leads go to a rectifier. Red and white leads go to a regulator. White lead pigtail goes to ammeter gauge and on to battery. I need to rewind but for the life of me I can't figure out how to connect the winding to the 4 leads coming...
  20. N

    Why does the displacement force act on AC - BC?

    Hi, I am having trouble understanding the intuition behind the problem I attached. Work is the product of the force and displacement in the direction of displacement, so since the crate is moving horizontally from A to B why isn't the displacement AB = 6m? Thanks in advance
  21. A

    AC Electricity Generation and Transmission over a Single Wire?

    I'm a bit confused as to why can't you transmit AC current over a single wire. For instance, say you have an AC generator which induces potential difference at different points of the wire and thus, creating current. Downstream, the wire can be split and applied to a load. When the wire is...
  22. J

    AC Cirucits - Impedance Values

    Homework Statement For the circuit given in the power factor is 0.72 lagging and the power dissipated is 375 W. Determine the: (1) apparent power (2) reactive power (3) the magnitude of the current flowing in the circuit (4) the value of the impedance Z and state whether circuit is inductive...
  23. berkeman

    Is there an AC Mains powered tire inflator? -- Updated

    I used to have a compressor that I used for keeping my vehicle tires inflated to the right pressures, but it was big and bulky (and I had to keep draining it between uses), so I got rid of it a couple of moves back. I'd like to be able to keep our vehicle tires topped off, without the bulk of a...
  24. L

    How to introduce a phase shift in an AC circuit

    Hello, I am trying to think of a way to introduce a phase shift in an ac circuit. For example, sin(omega*t+theta) to change theta. How can I go about doing this? I do not think introducing a cap or inductor would work, even though it shifts the voltage from the current graphs (phasors). A...
  25. Boltzman Oscillation

    In AC analysis do I alternate the current and voltage?

    Lets say I am analyzing a simple AC voltage source with a resistor. In the positive voltage peak then I will use V and I say current is flowing clockwise. When I am analyzing the -Vpk iteration then do I make the current counter clockwise too or do i keep it clockwise? Thanks.
  26. F

    Do transistors only work with DC and not with AC?

    Hello, I was reading an electronics book which state that transistors work with DC signals only (not AC), suggesting that relays are needed to switch AC signals. Is that a mistake? When used for amplification, I have seen transistors amplifying time-varying signals (which means AC). Unless...
  27. BabyHueyTAW

    Determining Number of Turns for low voltage AC Generator

    Ok, I did a quick search, and could not find answer. I need to determine how many turns / windings of 24awg magnet wire are required to generate no less than 5VAC no greater than 20VAC single phase using 3 of the N45 Neo Magnets rated at 13800 gauss each with 275-pound pull. Y'all give me a clue...
  28. Boltzman Oscillation

    Engineering What is the output voltage of this ideal diode circuit?

    Homework Statement Given the following circuit: what is the positive and negative peak values of Vo? vi has a frequency of 1kHz, peak of 5V, and is a sine wave. Homework Equations x(t) = Vsin(2(pi)*f*t) KCL, KVL, etc. The Attempt at a Solution [/B] I made Vi to be 5sin(2(pi)1000t) during...
  29. M

    Engineering Nodal analysis of an AC circuit

    Homework Statement Hi I have this question as part of my assignment but cannot get my head around part b, I have worked out part a with an answer of -9.2+17.3i amps which from a previous thread I know is correct, but can't understand why the equations given in the previous thread are different...
  30. A

    B Calculating the Uniform B Field in an AC Helmholtz Coil: What's the Formula?

    What would be the formula to calculate the right spacing distance between the coils in order to get a uniform homogeneous B field in the middle of the coils and how to determine the B field strength? I can only find bits and pieces on google about these sort of formulas but their intended for...
  31. S

    Hydrogen to AC -- From the Fuel Cell to the Grid

    Fuel cells quickly provide electricity from H2 when switched on. But what exact steps get to Grid voltage? Are there many small inverters, and if so, how do they keep the output in step? What sort of efficiencies are there?
  32. E

    AC to DC voltage doubler not working

    I have an AC to DC voltage doubler circuit. I am using a full wave bridge rectifier that uses two diodes and two capacitors that are 470uFarad each. My supply is a 50 watt transformer that outputs 13.9 volts and 3.790 amps. The supply frequency is 60 hz. The output frequency is 120 hz from the...
  33. akaf24

    Selecting a Motor for 600 RPM and 3 HP: Do I Need a Controller?

    Hello, for a project I need to select a motor which can rotate at 600 RPM with 3 HP of power. Do AC motors typically require a controller and drive? For example, I am interested in purchasing this. Do I need to buy an expensive controller just to operate it? How complex is the set up and...
  34. D

    Energy Efficient AC unit by returning air to the building

    Homework Statement You arrange your climate control system so that as it pumps heat out of the cabaret air and thereby chills and dries that air. Part of the heat your system removes from the cabaret air goes to the outdoor air and part goes back to the cabaret air. It turns out that delivering...
  35. Shivang kohlii

    Current through source in AC circuit with R & LC in parallel

    Homework Statement In the circuit diagram shown , Xc = 100 ohm , XL = 200 ohm , R = 100 ohm , the effective current through the source is ? Homework Equations Z= √( R^2 + ( XL - Xc)^2) Vrms = Irms/ ZThe Attempt at a Solution I tried to draw the phaser diagram and calculate the relation...
  36. archaic

    AC Circuit and Thevenin's theorem

    Homework Statement I'm asked to find the thevenin equivalent circuit, the load being ##R_1## ##e(t)=E_0\cos{(\omega t)}## ##R_1=1k\Omega \ R_2=R_3=1k\Omega## ##C=220nF \ f = 250Hz \ E_0=10V## Homework EquationsThe Attempt at a Solution ##Z_{th} = Z_{R_2}//(Z_c+Z_{R_3}) =...
  37. Kevin J

    B Are these AC circuits different? And does grounding change the voltage?

    The first picture is a regular ac circuit, where the voltage alternates between 240V/0V in one of the wire. The second picture is a live/hot & neutral ac circuit. Are these 2 different type of circuits? And if I connect the top circuit to the ground which makes it neutral (just like the pic in...
  38. P

    AC supply - Signal generator - CRO in circuits

    Hello, This problem is about a.c. I am used to simply using basic a.c. supply symbol in circuit diagrams. Here, I need to draw the set-up for an experiment where I can change the frequency of the supply (not the voltage) and see how this affect the peak current through a coil. how can i...
  39. K

    Mesh Analysis AC, solving simultaneous equations....

    Homework Statement Hi guys I'm doing the mesh analysis of AC circuit and looking for some guidance. Here is the mesh picture and some components data: Homework Equations Kirchoff's voltage law and current law.The Attempt at a Solution I decided that mesh currents are going in clockwise...
  40. Zahid Iftikhar

    Magnetic Field of an AC generator

    Hi Please help me in understanding the kind the magnetic field used in an AC generator. Most of the figures (one shown in attached file) are shown with concave poles. Hence the field has to be radial. In such a field the angle between plane of coil and the magnetic field remains zero all the...
  41. G

    AC generator output voltage to grid question

    Hi, In a given area there are different types of power plants , let's assume they are (coal, nuclear, wind and solar) Now as I have learned most of these plants (except solar and some others) use synchronous generators as the last step between mechanical energy conversion into electricity. But...
  42. anorlunda

    Automotive How does AC temperature control work in my Toyota Camry?

    When I use the air conditioner in my Toyota Camry, and I move the temperature control towards warmer: Does it make the AC cycle on/off thus saving fuel? Does it mix warm air with the cold, thus saving no fuel? I couldn't find an answer to this on Toyota forums.
  43. Wrichik Basu

    How can an appliance work better when the AC Mains stabilizer is removed?

    I don't know whether this question is suited to this forum specifically, but since it deals with electronics, I am putting it here. We have an old air-conditioner, bought in 2007. As you can understand, it is one of the old models running on R22 gas and it switches off the compressor when the...
  44. TechTree

    Is power lost in an AC adapter?

    Hello, so I'm rather new here and I was wondering when I plug a USB device into an AC adapter, such as a phone how does it output exactly 5.2V and 2A? I'm aware that it goes through a transformer and rectifier but I heard somewhere that when the voltage is reduced the current is increased? Does...
  45. J

    Engineering AC Source driving an RLC circuit....

    Homework Statement 10 v, 100 hz goes into a circuit of a 1o resistor, a 1o inductive reactance and a 1o capacitive reactance that are in series. What is the current. What is the V across the cap. Homework Equations and the attempt at a solution[/B] So I know I = V/Z and Z = sqrt( R^2 +...
  46. S

    AC Mains Power conditioner question

    Does anybody here have experience with whole house power conditioners? We live in an old neighborhood with old overhead powerlines, and it's been a rough fall for brownouts and other little transient "interruptions". I already have UPS's on delicate stuff (basement server, PC, home theater), but...
  47. cpcoe

    AC vs DC servo motors in large scale cable robot design

    hi, I'm designing a 50ftx50ft, 8-cable Cable Driven Parallel Robot and am thinking this is a pivotal decision. the corner posts are 10ft tall and the machine should be able to lift 100lbs at least 5ft off the ground. traveling speed of the end effector is less important than accuracy but I'm not...
  48. J

    Bench test AC transformer from stereo tube equipment

    I would like to disconnect the secondary windings from a stereo preamp to test the voltages of the secondary windings. The transformer has a 330 - 0 - 330 volt center tapped secondary and a 10.9 volt secondary. It is to be used with house current - 110 or so in Virginia. I have measured the...
  49. P

    Why don't voltages add up numerically in an LCR AC circuit?

    The attempt at a solution (Assuming the components are in series of this order: resistor, inductor, capacitor So I know that the phases are not in sync, that as the voltage oscillates the voltage across each component in the circuit is different. At the peak voltage aka peak current the voltage...
  50. A

    AC circuit, voltage and frequency problem

    Homework Statement According to Equation 20.7, an ac voltage V is given as a function of time t by V = Vo sin 2ft, where Vo is the peak voltage and f is the frequency (in hertz). For a frequency of 64.7 Hz, what is the smallest value of the time at which the voltage equals one-half of the...
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