Voltage Definition and 1000 Threads

  1. M

    Does Mutual Inductance Affect Voltage in an Open Circuit?

    Hi, so my question is basically: Does the mutual inductance from coil 1 show up in the voltage of coil 2 even if coil 2 is an open circuit? I would think that the answer is yes, as the Mutual inductance depends on the current passing through coil 1? However, the answer scheme seems to ignore...
  2. Rob45327

    What are the voltage and current in motor brushes?

    Summary: I'm rewiring an antique 1 amp universal motor (AC or DC). The two field coils need new brush leads so I have to buy new wire for them and I don't know the voltage. If the motor is running on 110 Volts is it 110 volts at the brushes? The motor is speed is variable and mechanical...
  3. runningman19

    Design of an Op Amp Circuit for Voltage Amplification

    Hi Everyone, I would like to measure voltage output from a sensor via an Arduino. The sensor outputs 20 mV at max capacity. I'd like to bump this up to around 5 volts so it is easier to measure. My plan was to use a non-inverting topology coupled with an LM393N op-amp. The schematic for a...
  4. 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.
  5. cianfa72

    Galvanic cell - open circuit voltage and EMF

    Hi, having not a deep knowledge of electrochemistry I've some doubts about processes involved in a galvanic cell. Take for instance a Zn/Cu Daniell cell for which E0cell is 1,10V. That means emf for it is 1,10V. Starting to read from how battery works I had a first understanding of how...
  6. Tesladude

    What is the voltage across this capacitor, inductor and resistor?

    I can solve for the questions in completely series or parallel circuits however having the capacitor and inductor in parallel while the resistor stays in series is stumping me completely.
  7. EEristavi

    Why a DC power supply doesn't have a voltage with respect to ground?

    I see that DC power supply have voltage between it's + & - and its 24V. However, there is no voltage with ground. I don't understand - if device's "point" has some potential, why doesn't it give some voltage with ground (which has ~0 potential) I tried this with phoenix contact...
  8. T

    Why can an electron go through PVC insulator

    I connected a PVC insulated alligator clip test lead to a 12V (give 20V) DC power supply positive terminal and a multimeter. After that I connected an other one to the multimeter ground, and a third one to the power supply negative terminal. I turned the multimeter to DC V measure mode. When I...
  9. N

    Electrical Where Can I Find a High Voltage DC 30kv - 40kv Generator for My Experiment?

    Hi all Trying to carry out an experiment and need a high voltage supply Looking for say upto 40kv dc adjustable generator been looking on the net and only able to find low cost voltage boosters on eBay Or if anyone know of a good website to try Any help would be much apreciated Thanks...Niki
  10. R

    What Are the Best Data Loggers for Monitoring 3-Phase Low Voltage Parameters?

    Could someone please suggest types of data loggers that can be used to log 3 Phase parameters on the Low Voltage side of a transformer. Thanks
  11. C

    Semiconductor physics: Voltage below forward voltage

    Assume we have a diode closed circuit.We connect the p type region of the diode to the positive terminal of the battery(cathode).We connect the n type region of the diode to the negative terminal of the battery(anode).The voltage of the battery is 0.3V .The diode%s intristic se miconductor is...
  12. E

    Line voltage in 3 phase as single sine wave

    Howdy all. The typical image of a three phase electrical system involves 3 sine waves, phase shifted 120 degrees. These sine waves each, individually, represent the 'phase voltage,' which is to a common neutral in a wye configuration. In this wye configuration the line to line voltage is...
  13. A

    Automatic Voltage regulator rating

    Hello Everyone, I'm here in a country which has a 220v single phase. My wife's $700 Microwave/Convection oven just arrived from the US. The rating of this appliance is: 110v, 1750 watts, 15 amperes. I've talked to suppliers here and was told to buy an AVR with a rating(wattage) 5 times more of...
  14. C

    Electrical Minimum conduction voltage between aluminium plates exposed to air?

    Hi, just thinking about a possible project and it may involve bolting aluminium plates together and putting a very small voltage across them. If I take two plates of aluminium, leave them to oxidise in air (we all know Al forms a surface layer) then is there a minimum voltage that will flow...
  15. P

    Fault in ungrounded system -> zero sequence voltage

    Hi. After some study, I came across symmetrical components. I found the attached schematic below on the internet, and will use it to explain my question. Question: Imagine that a single-line to Earth fault occur in one of the phases, i.e. resulting in an unbalanced system (we assume it was...
  16. F

    Engineering Help me finding the current in here please (Circuit analysis)

    Hi! I've been struggling with this. Original exercise here: Find the value of Iy when R=0. And the value of Vx when R is infinite. For the first part of the question I did this since R=0: I've tried to solve this circuit and I get that Iy and I5 are 0 A, and this can't be possible since Iy...
  17. P

    Voltage measurement of a point charge

    If we have a point charge of significant value, would osciloscope measure voltage if we just point the electrodes in two diffrent point in space?
  18. M

    What should I consider when searching for a high voltage power supply?

    I'm looking for a high voltage power supply. I have no experience with such a power supply, nor with all the terms or specifications used for such tools, so I'm looking for general suggestions to what to look for. I want to generate an electric field or potential field between two points a few...
  19. tinesi

    Voltage, electric field and potential energy for concentric shells

    1. Homework Statement the a shell is charged Va=120v shell b is grounded, Vb=0V What is the voltage in the center of shells (vo)? The electric field in the center of shells? The potential energy in the center of shells? Homework Equations Vr=Va+(1/r-1/a)/(1/a-1/b)Vab (from integrals) though I...
  20. X

    Calculate the maximum voltage that can be applied

    Homework Statement A detector of radiation called a Geiger-Muller counter consists of a closed, hollow, conducting cylinder with a fine wire along its axis. Suppose that the internal diameter of the cylinder is 3.00 cm and that the wire along the axis has a diameter of 0.2 mm. If the dielectric...
  21. M

    Why does an increase in voltage cause faster electron flow?

    In a circuit with a set resistance, let's say 1 ohm, the current flowing through the circuit is the same as the supply voltage. Why does an increase in voltage at the supply cause the electrons to flow faster?
  22. german_cargo

    Replacing a remote with a switch -- voltage drop problems :(

    I have a linear actuator that raises and lowers my snow plow blade and the wireless remote stopped working. Rather than order a new one for $200, I decided to splice into the wiring and put a momentary switch in my truck. I didn't like the remote anyways. I grabbed some wire and wired up a...
  23. P

    Finding the current and voltage for each resistor

    Homework Statement Moderators note: link removed. All images should be uploaded to PhysicsForums. Homework Equations V=IR Series in parallel Series in current The Attempt at a Solution I managed to get the current and voltage of R1 and R2. I've been trying to get the next one R3, but haven't...
  24. N

    Deriving Voltage from the Inductor Equation

    Homework Statement L = 20mH = 20 x 10-3 H i = 40 mA for t≤0 i = A1e-10,000t + A2e-40,000t A for t≥0 The voltage at t=0 is 28 V. I have to find the equation for the voltage for t>0. Then I have to find the time when power is zero. Homework Equations v(t) = L* di/dt p(t) = L*i* di/dt The...
  25. archaic

    Load resistance in voltage regulator

    Homework Statement [/B] I want to find the minimum resistance ##R_L## so as to maintain ##V_z##(voltage of the zener corresponding to the minimum current ##I_{z_0}##) across the same resistor ##R_L##. Homework Equations ##V_z##(voltage of the zener corresponding to the minimum current...
  26. Muhammad Usman

    How does a Capacitor protect against voltage spikes?

    Hi Everyone ! I have one confusion regarding the role of the capacitor in the circuit. How does the capacitor protects the circuit from the high voltage spikes. If the capacitor is connected from the circuit with battery. And sudden high spikes come then the capacitor is charged and the energy...
  27. K

    Required voltage for this large saw (German three phase schematic)

    Hi.. I am trying to figure out the required voltage for an Austrian built saw. I am not very good with AC plus the schematics are in German, I think, which is further confusing the matter. Here is the saw: http:/altpubad.com/Temp/1265-1994.pdf I assume it uses three 240 lines but thought I...
  28. K

    B How a Secondary Resistor affects the Transformer Primary Side?

    Let's assume a 2:1 transformer which has a 100V Source connected on the primary circuit and has no/negligible resistance, on the secondary circuit a 5 Ohms resistor is connected. Using the 'Impedance Transfer/Reflection' method, the primary circuit would act as if there was a 25 Ohms resistor...
  29. BabyHueyTAW

    Electrical Low Voltage AC-AC or AC-DC Step Up

    Ok, So my generator is producing ~1.5VAC. I need to step that up via transformer to no less than 5VAC max of 20VAC. Ideas or links to components I can use?
  30. G

    How to treat the "ideal" plate capacitor more rigorously?

    Hi. The derivation of the capacity of an ideal parallel-plate capacitor is inconsistent: On the one hand, the plates are assumed to be infinitely large to exploit symmetries to compute an expression for the electric field, on the other the area is finite to get a finite expression for the...
  31. H

    How to regulate a DC voltage without interruptions?

    Hi! I learned that all or at least majority DC voltage regulators such as step down module work by interrupting DC at some intervals. However, if I am interested in continuous DC, is it possible to make such voltage regulator that doesn't interrupt voltage at given intervals? Or what would...
  32. R

    Finding the Voltage across a Resistor using the Node Voltage Method

    Homework Statement For the given circuit (see below), find the voltage across resistor 3. Homework Equations n-1 Kirchhoff's Current Laws for n nodes. The Attempt at a Solution Can anyone verify whether my KCL equations are correct? The mixture of source voltages with node voltages may...
  33. R

    Voltage around a loop, half inside a capacitor and half outside

    Homework Statement This is not a homework problem, I'm working through griffiths Electrodynamics on my own. Homework Equations when there is an emf source, since electrosatic fields integrate to zero around a loop The Attempt at a Solution The solution claims that since the integral of f...
  34. 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.
  35. R

    Finding the values of voltage and current in this circuit

    Homework Statement It's best if one looks at the picture of the circuit diagram. What we're given is a current of 0.25 A and two resistances of 20 and 30 ohms. Homework Equations Kirchhoff's Voltage Law, Kirchhoff's Current Law, Ohm's Law The Attempt at a Solution My attempt at a solution...
  36. H

    Electric arc: How to calculate the required voltage for a light bow?

    <Moderator's note: Moved from a homework forum.> Calculate the required voltage to produce a electric arc between 2 iron nails (distance: 3cm). I´ve read in the internet that you need 1 kV per mm. But how can I calculate this value, that I need 1kV per 1mm?
  37. 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...
  38. 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...
  39. S

    A change in the dielectric constant changes the current or voltage?

    hi everyone! i am not into physics, but need it now,i am a programmer workin on an IOT project...so kinda need help. i want to use a capacitor to see what passed between two plates...knowing, it is the change in dielectric after certain intervals...how do i measure the change at the other...
  40. Z

    How can I calculate the voltage between two stationary electrons?

    How do I work out the voltage between two stationary electrons a given distance apart apart? I understand the definition of a volt and I guess that I would need to use Coulomb's law and integrate with respect to distance. It would be great to see the maths though as the answer that I got seemed...
  41. F

    What Is the Difference Between Current and Voltage Amplifiers?

    Hello, Basic question: what is the difference between a current and a voltage amplifier? Naively, in principle, I would think that if either quantity is magnified, the other will be also magnified simultaneously. How can we magnify current without magnifying the voltage and vice versa? Thanks...
  42. T

    Small & Lightweight High Voltage Power Sources: Ideas?

    << Mentor Note -- thread moved to the Sci-Fi writing forum after starting in the technical forums >> Hey folks, I'm interested in the feasibility of providing high DC voltages (~kV) in a physically small and low mass package (~grams). The power source does not actually need to be very energy...
  43. Jason-Li

    415V to 11kV Transformer Voltage % regulation

    1. Homework Statement A 415V to 11 kV transformer has a rating of 200 kVA. The winding resistance and leakage reactance when referred to the primary are 0.014 Ω and 0.057 Ω respectively. (a) Determine the % regulation of the transformer at 0.8 power factor lagging. (b) In designing a...
  44. C

    Heating Effect of Electric Current-Transmit at High Voltage

    Homework Statement Why is it inefficient to use low voltage when transmitting electricity? Homework Equations P∝i2 P=Vi H=Vit P=Ri2 E/ti2=V/i These are all basically the same few formulas, but I wrote down all iterations of them. Anything from Joule's Law/Joule Heating The Attempt at a...
  45. M

    PDLC film on low voltage (3-6V)?

    Hello community, I am working on a device project that requires a stripe of roughly 6cm*2cm to hide something beneath programmatically. A PDLC film could do the job, but I need to find a way to power with a series of coin cells battery, something between 3 and 6V. All the PDLC films I found are...
  46. J

    Fourier transform of a power signal or a voltage signal

    Homework Statement By using Fourier transform, I want to calculate power of signal. I confuse that f(x) in attached equation represents voltage or power. Is that possible when f(x) means power to use Fourier transform. Homework Equations The Attempt at a Solution
  47. E

    Puzzled by how the Voltage is the same across different points

    If this is better for the HW section please tell me, sorry about that. So Voltage is the change in potential. I'm puzzled by how potential in circuits is the same along different points until we reach a resistor - at which point the potential changes. As in, if we take two points before a...
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