Voltage Definition and 1000 Threads

  1. R

    Calculating Voltage and Farads for Efficient Rail Gun Launch

    Homework Statement So the problem says a rail gun needs to launch a projectile having the set distance of of roughly 6.3m (this isn't a straight shot, its more of a parabolic arc) and it needs to move an object of weighing about 6.52g. So it asks Volts and Farads you would need to get this...
  2. C

    Engineering Solving for voltage in a circuit.

    Homework Statement Find the voltage across the resistor and confirm that power in this circuit is conserved. Homework Equations KVL KCL V=IR, V=I^2R The Attempt at a Solution I have no idea where to start with this. We haven't learned voltage/current division yet. I am getting thrown by...
  3. N

    Correct formula for induced voltage with a stationary coil?

    I'm making an AC generator with a stationary coil and rotating magnets. What would be the correct formula to find induced voltage at a certain rotation speed (along with the units)? All sources I've found are either non-applicable or do not explain what units to use. Thank you for the help.
  4. C

    Using a DC Motor as a Generator

    So I'm working on a senior design project and was trying to use a DC motor to charge a battery. The point is to allow for quick use to charge a phone or a laptop in circumstances where you need a quick charge. We have lead-acid batteries connected in series and parallel to give us: 14,000mAh...
  5. Marcin H

    Direction of current flow in KCL/Node Voltage Confusion

    Homework Statement ------------------ Homework Equations V=IR KCL/Node Voltage The Attempt at a Solution These are the solutions to some old homework assignments that my teacher posted, but I am very confused on the way he labeled his current flows in these problems. In the first picture...
  6. Adeel Ahmad

    Calculating Voltage and Current in a Series Circuit

    Homework Statement Find the voltage v and the currents i1 and i2 for the circuit below. Homework Equations V=IR The Attempt at a Solution I would combine the 10 ohm and 40 ohm, and the 18 ohm and 9 ohm, so that they are in series with the 6 ohm resistance. Then I would use V=IR to get the...
  7. Adeel Ahmad

    Electricity, finding voltage and resistance

    Homework Statement Design a voltage divider circuit to provide an output voltage v0 = 5V from a 12V source. The current taken from the 12V source is to be 100mA. a)Find the values of R1 and R2. b)Now suppose a load resistance of 200 ohms is connected across the output terminals (in parallel...
  8. S

    Kirchhoff's Law with Capacitors: Voltage, Resistance & Charge

    Hello! I am bit confused about kirchhoffs law with capacitors. So if I have a battery and resistance, I obtain V-RI=0. But from what I read, if I have a capacitor and resistance (so discharging capacitor), the equation reads R(dq/dt) + q/c = 0, which is equivalent to RI + q/c =0. Why in this...
  9. Glurth

    Odd troubleshooting results: disobeys ohms law

    I have a DC powered pump, that has suddenly stopped working. During troubleshooting I came up with the following results, that I just cannot reconcile: Input wires, not connected to pump: 12v Input wires connected to pump: 0v Sounds like a short in the pump right? However, connecting the...
  10. Borek

    What is the purpose of a capacitor in a voltage divider circuit?

    I need a voltage divider to make it possible to measure voltage on the 3S LiPo battery that delivers around 11 V using a device that measures up to 4 V (approx). I can make one, no problem, just solder two resistors with resistances in the more or less 1:3 ratio (measured output is sent as a...
  11. G

    Category ratings on test gear (maximum voltage)

    Hi all. What does the voltage rating in each category I/II/III/IV actually mean? For example, my multimeter is Cat III rated to 300V. Is this RMS? Peak? Peak-peak? Our supply here is 230V RMS AC, but this means the momentary peak is about + and - 330V (relative to neutral/ground) and the...
  12. K

    AC Output Voltage as function of frequency

    Homework Statement Given a sine-wave generator of frequency f having internal resistance R1 connected to a high-pass filter. If the generator shown in the dotted outlined box produces a voltage V0(t) = V0 cos(2π ft) with no load, derive an expression for the output voltage V1(t) = V1 cos(2π ft...
  13. Marcin H

    Engineering Open Circuit Voltage and Short Circuit Voltage

    Homework Statement Homework Equations V=IR Current Loop method, KCL, Node Voltage The Attempt at a Solution I am struggling with this problem because I haven't seen a circuit like this before. I think I found the Voc correctly (4V) but I am stuck with finding the short circuit current. I...
  14. Marcin H

    Engineering Bridge/Ladder Circuit and Node Voltage Method

    Homework Statement Homework Equations Node Voltage Method V=IR The Attempt at a Solution So I have never worked with a bridge/ladder circuit before and I am not sure if I am doing it correctly. My professor never gave us an example of a bridge/ladder so I'm kinda winging it. Anyway can I...
  15. K

    Why Does Moving a Negative Charge to a Higher Potential Increase Its Energy?

    Homework Statement When a -2C is moved from point A to B, the potential energy of the system increases by 10J. What is the voltage V(ab)? Homework Equations U=qV The Attempt at a Solution 10=(-2)V, I thought the voltage was -5V but the correct answer is +5V. Could someone explain why this is?
  16. C

    Soldering High Voltage Capacitors

    Hi guys! I am fairly new to the forums so thank you for having me here :) I just wanted to ask some of you guys here who have a better knowledge about high voltage capacitors than me. I am creating a lightning impulse voltage generator as my final year project and have been provided with most...
  17. Arjun Mehta

    Need to know about Surface Voltage

    If we apply an electrical insulating material on a bare conductor which carries 25 Kv AC Voltage. What would be the surface voltage observed on the insulating material? Is there any test/method by which surface voltage can be measured on the Insulating Material. The Insulating material has...
  18. J

    How to find Pmax when you know voltage and current?

    Homework Statement After t=0, the current entering the positive terminal of a flashlight bulb is given by: i(t) = 2(1-e^(-10t)) A and the voltage across the bulb is v(t) = 12e^(-10t) V. Determine the maximum power level delivered to the flashlight. Homework Equations i(t) = 2(1-e^(-10t)) A...
  19. G

    The true meaning of voltage drop

    In CE amplifiers with negative feedback I can't understand what it means that the emitter becomes more positive (when hfe increases and VE increases with it). Does it mean that there is less negative charge after the emitter resistor (going from ground to Vcc) and the emitter feels some positive...
  20. G

    Discharge only one plate of a capacitor?

    Hi. Assume we connect both plates of a capacitor to ground and disconnect again, leaving them at ground potential. Then we bring electrons from one plate to the other, until there is a voltage difference ##\Delta U## between the plates. Compared to ground, one plate has the potential...
  21. L

    Power and voltage are the same thing?

    I am a student of Electrical . but I am not clear about power and voltage. Is any rapport between them ? I read about this two things . but i can't solve it. Is anyone tell me easily about this topic?
  22. Metals

    How to find power dissipation of a resistor in this circuit?

    Here is an image with information: https://i.snag.gy/UMCRig.jpg I have calculated the total power dissipation as 11W. What I don't see is why R1 has a higher dissipation rate than R2/R3, and my main question is how do I calculate the power dissipation of R1? I get that R2/R3 are in series so...
  23. B

    How Can We Measure the Speed of Light Over a Long Distance?

    The main question stems from the answer for this one: If I have a light year long rod and push it on one end, how long would it take for the other end to move? Still Unsure of this answer. Main Question: If I had 2, light-year long conductive rods with a voltmeter attached at the ends then...
  24. S

    About Voltage, Current and Ground

    First of all , I'm a completely new to this current - voltage concept , I have problems understanding Grounding and the current flow in circuits . 1) Which path do currents take when there are multiple grounds in a circuit . 2) How and where should a circuit be grounded and why ? 3) Why is...
  25. T

    RC circuit, finding voltage across a capacitor

    Homework Statement I am trying to find the capacitor voltage in the following picture: Find i(t) in the figure below. Assume dc steady state conditions are valid for t<=0. Homework Equations i=c(dv/dt) KCL The Attempt at a Solution At t<0 I found Vc to be 8 volts which should be correct...
  26. F

    Why do electronic devices have a maximum voltage limit?

    Hi, I'm learning the basics of EE, and I never fully understood voltage and current. So, in a very simple circuit, if we increase voltage, the rate of elétrons will increase due to the increase of the force that "moves them" right? Then in the end, voltage's only purpous is to manipulate...
  27. D

    Solar Panel Voltage Boost Troubleshooting

    Hello, I Have built a 50w solar panel that gives an output of ~ 9.2v @ 5-6 amps during a good day. This is not enough to charge a 12v battery. To get around this, I am trying to use a DC-DC boost converter (specifications are below) and it is set to give an output voltage of 13.5v. The only...
  28. Y

    Why does putting two batteries in series increase the voltage?

    So say we had 2 batteries, B1 and B2, and B2 is on top of B1. The + terminal of B1 connects to - terminal of B2, and the + terminal of B2 connects to - terminal of B1. Why does this double the voltage compared to the voltage of just B1?
  29. psuedoben

    Conductivity of saltwater dielectric vs current

    My partner and i have been running experiments for our research in micro algae separation, using a reactor containing aluminum electrodes. we run a 10v current across the electrodes, and flow saltwater between them. we were wondering how changing the conductivity of the saltwater might affect...
  30. T

    Is voltage drop different in parallel circuits?

    https://puu.sh/qzv6o/5abc45494b.png I was under the impression that voltage drop was the same in parallel which would make it the power supply, but apparently not? Any insight would help. I know this isn't a hard a question, I'm just horrible at physics.
  31. J

    High Voltage in a Cloud Chamber?

    Hello all! Firstly, thanks for reading this post! I am a high school student attempting to make a basic, dry ice cloud chamber. I have made several cloud chamber designs and I am about to start making it. However, before constructing the product I would appreciate some members to provide...
  32. G

    How Does Voltage Affect Diode Current Flow?

    I want to make something clear. Most diodes have in their datasheet some current for a given treshold voltage. For example a led will pass 20mA current when 4volts are applied to it. Or a zener diode's minimum turn on current is 10mA when 5,6 volts are applied across it. Does this mean this...
  33. F

    Question about LEDs relative to voltage

    Back story : I have cheap 12v LED 5050 strip from China. Question: how do LEDs respond to 13v and 14v in terms of % intensity with higher voltage neglecting lifespan and assuming proper heat dissipation. Details: the LEDs at 60/m rated 14.6w at 12v. They are typically 3led in series with a...
  34. G

    B Why can you choose only V in DC but V and I in AC?

    Hi. Assume we have some circuit with resistance ##R##. In DC, the current ##I## linearly depends on the connected voltage ##V## by Ohm's law ##I=V/R## . In AC, we can independently connect any voltage and current to the system by using a transformer, provided we have a power source with...
  35. Enochfoul

    How Do You Calculate Output Voltage Range for an Adjustable Voltage Regulator?

    Homework Statement [FONT=Thread-000016e0-Id-00000031] [/B] Calculate the output voltage range for the adjustable voltage regulator circuit shown in FIGURE 1. I have read an older post and have understood how the formula works but I am thrown off by the inclusion of the 50uA current coming...
  36. Clara Chung

    Please further explain this formula about voltage

    Homework Statement On the right bottom side ,when the switch is closed the equation is given V(EG)=+V+V(FG) The photo is attached Homework Equations Concept The Attempt at a Solution What is the difference between the back emf in the inductor and the p.d across the inductor? I think the...
  37. C

    Question on Laplace Transform of a constant voltage source

    Hello. I am reviewing the use of the Laplace Transform to do circuit analysis and I am slightly confused about the transform of a constant voltage source. For example, let's say we have a constant voltage source V1(t) applied to a circuit for a long time - let's say it reaches steady state. We...
  38. J

    Engineering Determine the open circuit voltage for VL

    Homework Statement See image attached Homework Equations Voltage divider law? Ohms law? The Attempt at a Solution I am unsure on how to treat the problem since I have only learned how to find information within parallel circuits and series circuits. I tried to use the voltage divider law...
  39. O

    Why does a voltmeter measure a voltage across inductor?

    The potential difference across an inductor is supposed to be zero, but a voltmeter measures it to be L*dI/dt. Also, if the p.d is zero then the electric field in the wires of the coil will be zero and in that case, why should charges flow at all? What am I missing?
  40. A

    Uncovering the Mystery of Voltage: A Comprehensive Explanation

    Hello, i was wondering if somebody could give be a better explanation of what voltage really is. Its has been explained to me that the voltage of an electron can be thought of as holding a ball at certain height representing the potential energy of the ball which is then converted into kinetic...
  41. nishant mudgal

    Is Powerline Voltage Always an Integral Multiple of 11?

    Why is the supplied voltage in the powerline wires an integral multiple of 11 from the supplier? Example -- That line is 11,000V
  42. SSGD

    Microcontroller Pulse Width Modulation to Analog DC Voltage

    What are some effective ways to convert a Pulse Width Modulation from a Microcontroller to a DC Voltage as a function of Pulse Width? 1. Use a low pass filter to remove the unwanted harmonics and leave only the 0th term of the Fourier Series. What produces a better DC Voltage an Active or a...
  43. Buggsy GC

    Why do weaker capacitors have the the largest voltage acros

    Homework Statement A voltage is applied across the capacitor network in the image shown Below (if it loaded I can only see a small panel with IMG on it), which of these individual capacitors has the highest voltage across it Homework Equations...
  44. Delta2

    Do Moving Charges Create Magnetic Fields, or is it Something Else?

    Ok so when we have a current carrying conductor inside a magnetic field there would be Laplace force ##L\times Bi## which is the macroscopic form of the microscopic Lorentz force ##v\times Bq## in a large number of electrons ( or it is not ?) But also there will be hall voltage which will...
  45. G

    220V 50Hz Equipment vs. 230V 60Hz Equipment compressor

    If If you have a compressor designed for US 60 HZ 230 V what are the risks with applying it in 220 V 50 HZ ? I understand there will be a ~20% derate in power but are there any safety or failure concerns ? would the lifespan of equipment change? Do I need a transformer ? This equipment...
  46. R

    Vibrational frequency of Piezoelectric effect

    when a piezoelectric material experience a stress it generates voltage, and also when you applied voltage the piezo-material experience a vibrational frequency. Using oscilloscope we can determine the induced frequency of the piezo-material with respect to the applied voltage. Now given the...
  47. I

    Generating High Voltage: Safe and Effective Methods for Amateur Use

    Good Afternoon everyone, Question: What are some effective ways to generate a high voltage (Multiple KV) using amateur equipment? I've dealt with high voltage before, so I'm aware of the safety issues. Anyway, here is what I've got thus far: If you go on ebay, and search for high voltage power...
  48. B

    Engineering Zener voltage controlled circuit design

    Homework Statement Homework Equations V0=Vsrz/Rs+rz+VzoRs/Rs+rz-ILrzRs/rz+RsThe Attempt at a Solution I formulated 4 cases for voltage inputs of 11 and 13.6 V and 0 to 100 mA. The zener current has to be between 3 and 30mA or 103 and 133mA. How can the current be maintained in thes two...
  49. B

    Finding voltage change for current change for diode

    Homework Statement Find the change in diode voltage if the current changes from 0.1 mA to 10 mA. Ans. 120 mVHomework Equations V2-V1=VTln(I1/I2)The Attempt at a Solution That is all the information given. The only equation I can think to use is the diode voltage/current relationship, but a...
  50. K

    Effect of voltage on resistance wire life expectancy?

    I am using a 30kW air heater which is using resistance wire. I am not exactly sure what type of wire it is and hope this will not be an issue in answering this question. The heater is rated at 380V and 45amps(max)...my supply is 415VAC (+ 6% and - 10%) and 45amps. Any idea if this extra...
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