Voltage Definition and 1000 Threads

  1. A

    11kV vs 22kV electric distribution voltage

    Hi, what are the possible reasons for selecting 11kV underground distribution system vs 22kV underground distribution system for urban area. I know about 22kV can carry twice the load compared to 22kV. How about impacts of pricing, fault level, stepdown from 132 kv to 22/kv etc. Thanks
  2. F

    Non-Ideal Battery Voltage with few data points

    Homework Statement The problem includes a graph. All I have is a current to external resistance graph, with 20 A coming at 10R of external resistance. I am to find the EMF and internal resistance of the battery. Here is the problem and my two attempts. http://1drv.ms/1LKbu5H Homework...
  3. K

    What is the voltage gain for this circuit?

    Homework Statement assume β=200,Vt=26mV,Vbe(on)=0.7V Find the voltage gain Vo/Vs How to find the Rth , Vs ,then find the voltage gain? I try to draw the circuit diagram below Homework EquationsThe Attempt at a Solution Vth=[R2/(R1+R2)]*15 Vth=1.63V Which method should I use to find Rth...
  4. S

    What is the Voltage Gain of Vo/Vi in an Op Amp Circuit?

    Homework Statement Find the voltage gain of Vo/Vi. I'm pretty confident I have this down now, but I'd be greatful if someone could confirm I have this sussed. Homework Equations For the inverting op amp: Vo= \frac{-R2}{R1}*Vi For the differential op amp: Vo= \frac{-R2}{R1}(V--V+) The Attempt...
  5. G

    Calculating Input Voltage for Switched Op-Amp Circuit

    Homework Statement Calculate the input voltage to an Op-Amp circuit. The circuit is exactly an ideal non-inverting amplifier except the inputs have been switched in that the supply is connected to the inverting input and the middle of the potential divider is connected to the non-inverting...
  6. psparky

    Is Voltage Gain Squared Equal to Power Gain in the Log Domain?

    Hey guys, I need confirmation on this. Since V=IR and P=IV...and V^2/R=P Lets say your body has a resistance of 2000 ohms and you get shocked by 120 volts. You receive 7.2 watts of power. Now let's step to the left and get shocked by 480 volts with the same 2000 ohm body. I now get 115.2 watts...
  7. ifan davies

    Determine: The r.m.s. ripple voltage

    An aircraft electrical system operates at 115 volts at 400 hertz. It is to supply an average d.c. voltage of 28 volts and an average current of 20 A at a ripple factor of 0.005. Determine: The r.m.s. ripple voltage Here is my attempt. Vc= Vs-2Vd =28-2(0.7) = 26.6 Volts Vr= (1/2 x fs x C...
  8. P

    Can a 12V DC Source Efficiently Charge a 16.9V Lithium Ion Battery Pack?

    Hi, I have built a large, lithium ion battery bank, so that I may power some of my projects from battery. The bank is 10,000 milliamp hours at 16.9 volts, and was wondering the following. Can I charge my 16.9 volt battery pack with a 12 volt dc source? would It decrease the efficiency? Would...
  9. S

    How do Capacitors and Inductors Add/Remove VARS in AC?

    To my understanding, capacitors cause the current to lead the voltage which adds VARS to the circuit and inductors cause the current to lag behind the voltage which removes VARS (in AC circuits). Also, it is my understanding that VARS increase voltage. I work for one of the largest utilities...
  10. kostoglotov

    Thevenin Equiv with just Capacitors

    Homework Statement imgur link: http://i.imgur.com/TWB5rRu.png Homework EquationsThe Attempt at a Solution I can find the equivalent capacitance, 10F, but I'm not really sure how to find the equiv. Thev. voltage. I figured that with the voltage source present, half the voltage will be lost...
  11. kostoglotov

    Understanding the Integration of i(t) to Find V(t) on a Capacitor

    Homework Statement imgur link: http://i.imgur.com/zGhum8Q.png The answer given in the back of the text is imgur link: http://i.imgur.com/hAprWPV.png Homework Equations v(t) = \frac{1}{C_{eq}}\int i_s dt The Attempt at a Solution I get the last piece of the piece-wise v(t) to be...
  12. U

    Variable Voltage Transformer for Wind Turbine Battery Charging?

    We are trying to build a wind turbine which will charge a battery. Since wind speed varies (which affects the generated current and voltage), we were going to integrate a transformer in. My question is does such a transfomer even exist where the input voltage varies while the output voltage is...
  13. S

    Can you measure voltage of AA batteries while they operate?

    I'm wanting to know if I can and if so how to measure the voltage of two AA batteries whilst they are in a device with the device turned on. This device is a vibrating toothbrush so if anyone could help with an answer, it would help teremendously with my science project as I am testing the...
  14. Mr Davis 97

    How does increased conductivity affect voltage?

    If I have a certain circuit set up with a voltage V, then how does increased conductivity in the wire affect the voltage, or does it? I know that increased conductivity affects current, but if Ohm's law is to be true , voltage must increase or resistance must decrease. So which is it? Is voltage...
  15. C

    How Do Relative Voltages Affect Tube Operation in Amplifiers?

    I have a question about relative voltages and operating points of components, in this case tubes. Are these two functionally the same? For a while now I never could understand how the bottom triode of the WCF in an amp I bought was biased at -100v on the grid and 0 volt on the plate which...
  16. C

    Engineering Basic circuit operation of voltage regulator

    Homework Statement Homework EquationsThe Attempt at a Solution I need to know if my understanding of this circuit is correct in terms of R1, R2, Q1, Q2. R1 is a sensing resistor and when Q1 senses a voltage drop at its base, it switches on and passes current around the regulator. I think...
  17. Y

    Three-Phase Delta Network: Not all Voltage Sources are 120V?

    Using the Delta Netowrk from this image: http://www.belden.com/images/B23_WyevsDelta.jpg Between Y-X, there should be 120V. Between Y-Z, there should be 120V. Between X-Z, there should be 120V. But wait! If we assign values to make the above statements true... Call X = 0V, and Y = 120V, so...
  18. S

    Measuring Voltage across Resistor in Series RLC Circuit

    I was experimenting with resonant frequency of a series RLC circuit: 5V AC source 10 ohms resistor 100microF capacitor 46mH inductor Resonant frequency is calculated to be around 74.2Hz. So I set the AC source to resonant frequency 74.2Hz and measured the voltage across the 10 ohms resistor...
  19. nothing909

    Engineering Calculating voltage across resistors/capacitors in a circuit

    Homework Statement Calculate the voltage across each resistor and capacitor in the circuit. Homework EquationsThe Attempt at a Solution As shown in the pictures, I have calculated the combined impedance of all the resistors and capacitors in the circuit. I then calculated the supply current...
  20. V

    How Do Charges and Voltages Distribute in a Circuit with Multiple Capacitors?

    Homework Statement A potential difference of V = 38.0 V is applied across a circuit with capacitances C1 = 4F, C2 = 5F, and C3= 2F, as shown in the figure. What is the magnitude and sign of q3l, the charge on the left plate of C3 (marked by point A)? What is the electric potential difference...
  21. 5

    The sign of the current and voltage

    I was doing the following problem: And I was asked to find Iy. I found Iy to be 2.64 using KCL. However, the right answer was negative 2.64. Is it negative only because there is a dependant voltage source with "+ -" ? And why must it be negative? Does "-" in the final answer play a...
  22. B

    High voltage charge & same polarity on two concentric rings

    I have a charged ring with a high voltage potential. As I see it the charges repel from each other and so position themselves around the outside of the ring. I want to push the charge to the inside surface of the ring and so I envisioned a 2nd ring positioned concentrically just outside this...
  23. H

    How to determine the breakdown voltage of a diode?

    Homework Statement The question is posted below. Homework EquationsThe Attempt at a Solution I don't know how to solve this question.Does the breakdown voltage of a diode depends on the voltage source near the diode?For example,breakdown voltage of D1 in (a) is 30V? Also, I don't know how to...
  24. F

    Voltage drop across voltage divider

    Homework Statement A voltage divider with two resistors R1 and R2 is given. The output is connected to a transistor so VB is always equal to the base emitter voltage=0.7v. Homework Equations How can i explain physicaly (wath happens to the electron flow and such) why when R1 is verry high, VB...
  25. neilson18

    Find an expression for the capacitor voltage

    Homework Statement [/B] An uncharged parallel-plate capacitor with spacing d is horizontal. A small bead with mass m and positive charge q is shot straight up from the bottom plate with speed v_0. It reaches maximum height y_max before falling back. Then the capacitor is charged with the bottom...
  26. Salvador

    Electrolytic capacitor voltage headroom

    Hi , I'm in need for some 10+ caps for my smps secondary side smoothing. the thing is electrolytics are not cheap , so I need about 1000uF a piece but there is a big difference between whether it's 200v rated or 100v rated. the voltage across the each cap would be about 92v DC , I wonder would a...
  27. G

    Why does Piezoelectric output voltage dropped when load is added?

    Hi, im doing a piezoelectric energy harvesting project with a standard harvestings circuit consisting of a full bridge rectifier, smoothing capacitor and a resistive load. I managed to get around 28V after rectification without connecting to a smoothing capacitor and load, but when i added a...
  28. Marcin H

    RL circuits: Find the voltage through the resistors

    Homework Statement Find the voltage through the resistors. Homework Equations V=IR P=IVThe Attempt at a Solution Am I doing these correctly? Can I find the voltage across the inductor the way I did it?
  29. J

    Voltage Difference Along a Path

    Homework Statement Given the electric field E = (2x−y2)ax + (3z−2xy)ay + 3yaz, and the piecewise linear path joining the points A(−2,1,−1), P(2,1,−1), Q(2,3,−1) and B(2,3,1), find −∫E⋅dl from A to P − ∫E⋅dl from P to Q − ∫E⋅dl from Q to B along the straight line segments. Homework Equations...
  30. C

    High voltage voltage controlled linear variable resistor

    I have some high voltage (300v+) analog circuits that I want to control digitally which requires the use of a voltage controlled linear resistor that can withstand high voltages. I don't expect the current levels to be that high. I originally settled on LDR optocouplers but it turns out they...
  31. C

    Adjust supply voltage based on divider resistance

    Hello, I'm working on a project and I need some assistance. I need to adjust the negative supply voltage to an integrator opamp that I use for DC offset control based upon the resistance in a voltage divider elsewhere in the design. R12 is the trimmer resistor to adjust the CVS circuit and V5...
  32. C

    Can You Help Me Achieve a 5x DC Gain for Opamp Output Voltage?

    Hello, I need an opamp that can output +/- 150v without paying $500 for a high voltage opamp. I need a workaround solution, I'm thinking of a 5x DC gain of the opamp output voltage but I am totally clueless on how to achieve this. Any ideas?
  33. PhyBoy

    Solving Hall Voltage Problem Homework Statement

    Homework Statement [See the figure attached] a) Find the relation between velocity of electron v and current I. b) Because of the magnetic force on the electron they move at the edge of conductor as shown in the figure and create a electrostatic force that oppomagnetostatic force. Find the...
  34. gracy

    Question based on a video (battery and voltage)

    in all three cases there is no battery or voltage source,right?Because I can't see any battery.But there is voltage ,then without battery how is potential difference created?I think potential difference is generated due to charged capacitors not by battery or any other voltage source.
  35. Marcin H

    Equivalent Capacitance and Voltage Across

    Homework Statement Homework Equations Series: 1/Ceq=1/C1+1/C2 Parallel: Ceq =C1+C2 The Attempt at a Solution So to find the equivalent resistance do I short (put a wire through the open terminals) the circuit and start adding up the capacitors? Once I do that do I just create a new circuit...
  36. S

    How to Derive the Voltage Gain Transfer Function?

    Homework Statement Homework Equations The Attempt at a Solution
  37. N

    What is more effective -- Current or Voltage?

    I have fan that's 20 V and 14 A. I give it an input of 5V 1A. So my question is... increasing what will increase the performance of my fan more... Current or Voltage??
  38. R

    Kirchhoff's Voltage Law Integral help

    [SIZE=16px][FONT=Helvetica Neue]Consider the circuit from minute 6:57: [SIZE=16px][FONT=Helvetica Neue] So I have an electric field there everywhere in the loop and I can write integral of E*dl as being v and I end up with kirchhoff's rule. (you don't have to watch all the video to respond to...
  39. G

    Energy Calculations: P=VxIxt - Why Watts & not Joules?

    The question: Calculate the energy used by the lamp in 6 hours of use. The answer: P=V.I.t P= 240v X 0.2A X 6hrs X 3600s P= 1036800W!? I thought energy was Joules? Why has the answer been given in watts? Please help!
  40. Marcin H

    Node Voltage Method: Find Voltage Across 6A Current Source

    Homework Statement Find the voltage, V, across the 6A current source Homework Equations V=IR Node Voltage Method The Attempt at a Solution Did I set this up correctly to find my voltage?
  41. K

    How did they integrate the charge for Voltage question

    I have a question on finding potential for a disc of charge when it comes to the simple integration how does the integral of R'dR'/etc have the R'dR' just disappear? i thought it would then be R^2/2 I am obviously missing something here
  42. O

    Thermoelectric Modules: Heat/Cold Ratio for Voltage

    What is the heat/cold ratio in thermoelectric modules to generate a specific voltage pls? old Bozo
  43. D

    Finding Voltage graph from current graph of capacitor

    Homework Statement I am given the current flowing through a 2 micro-farad capacitor in the form of a graph, and I need to create a voltage graph from this. Homework Equations I = C dv/dt Q = VC The Attempt at a Solution The current graph is basic with a constant 4 mA from 0 to 4 microseconds...
  44. Marcin H

    Find voltages across resistors using voltage division

    Homework Statement 7a from picture Homework Equations V=IR Voltage division The Attempt at a Solution I am not sure how to apply voltage division here. It is a new concept for me and I'm not really sure how to apply it here. voltage division can only be used in series, but these resistors...
  45. G

    Piezoelectric strain rate and frequency of applied voltage

    If one were to apply, for example, 60 Hz AC to a piezoelectric material, would the strain rate be 60 Hz? I am not entirely sure if I am using "strain rate" in its proper sense; I use it merely to describe what I imagine would be the rate at which the material expands and contracts while exposed...
  46. C

    What Is the Maximum Power on an Impedance Z?

    Homework Statement Find the maximum power on a impedance Z. Homework EquationsThe Attempt at a Solution I got as Thevenin impedance Zt=4+j4 and Ut= 32 V, but since my solution for power is wrong, something is wrong with either impedance or voltage (or both). If point A is above Z, and point B...
  47. P

    Charging Super Capacitor w/Buck Converter: Max Voltage Draw?

    If I am charging a super capacitor with buck converter, that is a 1 amp, 1-18 volt output, and the capacitor is rated for 2.5 volts, how do I stop the buck converter from feeding it more than 2.5 volts? When I attach the capacitor to my digital power supply, it starts charging, and the voltage...
  48. STEMucator

    What Diode Has a Low Turn-On Voltage and Through-Hole Termination?

    Hi. I'm wondering if anyone knows the model number of a diode, which has a low forward turn on voltage, and has through-hole termination. I am aware of the BAT54 Schottky diode series. The turn on voltage is as low as ##0.2 V## for some models, but the problem is they are surface mount...
  49. C

    Ratio of effective and average voltage

    Homework Statement See the diagram. Find $$\frac{U_{ef}}{U_{avg}}$$ . Homework Equations [/B] $$ U_{ef}=\frac{U_m}{\sqrt3} , U_{avg} = \frac{U_m}{2} $$ The Attempt at a Solution This one should be easy.I know that official solution probably divided $$\frac{2}{\sqrt3} \approx 1.154$$ (which...
  50. AstroJMT42

    Voltage drop and transformer improvement

    Homework Statement Power station produces AC power at 2.5Mw, I = 100A. Transferred along 100km line with a resistance of 50 ohms to a factory. Calculate power lost and % efficiency Homework Equations P=VI P = I2R The Attempt at a Solution Initial power at the station is 2.5x106 . Using I2R...
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