Voltage Definition and 1000 Threads

  1. amizy9990

    A copper wire contains 3.0 *10 ^ 22 number of charges on 1 meter wire

    A copper wire contains 3.0 *10 ^ 22 number of charges on 1 meter wire. What speed do the electrons move when there is 2 A current in the wire. t=q/t=3,20*10^3 C/ 2.0 A = 1,5*10^22 s v= 1m/1,5*10^3s= 6,6*10^-4 m/s
  2. M

    I Checking for negative feedback in a circuit

    This is the circuit in question. During lecture, when checking whether this was negative feedback, my instructor said that if the v_out increases, then v- increases as well, which would lead to the next v_out decreasing because v_out = A(v+ - v-). I get how if v- increases the next v_out would...
  3. Lord Doppler

    Engineering Voltage Carrier Signal and Voltage Modulating Signal (AM)

    Hello everyone, I'm trying to find the Voltage Carrier Signal and Voltage Modulating Signal from the power spectrum of a AM signal 1) I change the scale dBW to W and I have this: From this I have that Pc (Power of the Carrier signal) is 50 W and I don't know how to continue with the...
  4. M

    Some questions about capacitor discharging

    why does the voltage of the capacitor eventually go to 0 when discharging the capacitor? I heard that's because "current starts flowing when discharging", but how exactly does that lead to V going down? I know that I = C * dV/dt, but that doesn't seem to help me understand why V goes down (which...
  5. Xiao Xiao

    Electric Circuit Analysis, Nodal Analysis and finding Voltage.

    Summary:: The image shows two circuits, in the first one, using Nodal Analysis we find that V1=4.8V, but in the second circuit V1=10 because using KCL - 10+V1=0. I understand what happened in the first circuit, but I don't understand what happened in the second one, they look the same to me...
  6. willDavidson

    Laplace Transform Finding Open-Circuit Voltage

    I am interested in modeling a battery charging/discharging. I am starting off with a simple model using a voltage source in series with a parallel RC branch which is in series with a resistor. I will be measuring the open circuit voltage between the last series resistor and the bottom of the...
  7. AN630078

    Transformer; make primary voltage x10 of the secondary voltage

    I understand that transformers function using electromagnetic induction and Faraday's Law. This implies; Vs=-Ns (dΦ)/(dt) Meaning the secondary voltage is proportional to the number of turns on the secondary coil. Vs∝Ns Using the relationship; Vp/Vs=Np/Ns If we want Vs=10Vp that would imply...
  8. P

    How does smoothing an AC voltage with a capacitor work?

    Specifically for part (i) and (ii), I get the rough idea that when the voltage of the AC source is decreasing, the capacitor can discharge to "cushion" the drop in voltage. However, I have some questions about when this occurs. 1. There is an assumption that the capacitor will be charged to...
  9. EQVan

    Solve for phase-to-neutral voltage in terms of phase-to-phase voltage

    First a disclaimer: I am neither an electrical engineer nor a mathematician. I am a programmer. As part of a simulator project, I've been asked to solve a particular problem -- and I'm in over my head. Given an unbalanced 3-phase AC circuit, I have learned that I can solve for the...
  10. HelloCthulhu

    What is the breakdown voltage for this two dielectric capacitor (BaTiO3,LPDE)?

    BaTiO3 thickness = 7mm = 0.007m dielectric constant = K = 1260 dielectric breakdown = E = 97MV/m (97kv/mm) (Structural, Dielectric and Ferroelectric Properties of Tungsten Substituted Barium Titanate Ceramics, 2009) LDPE thickness = d = 0.007m dielectric constant = K = 2.3 dielectric...
  11. Helena Wells

    Basic NMOS+Zener Current Source Test

    I have been trying for a long time to build a costant current source which I know is impossible to keep the current exactly the same but as much as possible. This is what I have done so far: The operation is very simple . If VCC is increased the VAC is increased a little bit. When VA is...
  12. D

    AC - Node Voltage Method for difficult circuit

    Hi! I'm trying to understand and solve this circuit by Node Voltage Method. I have to calculate u(t). In my mind, I don't have any idea if any current should go through Z1 in my calculations. I would be grateful if you could write even equations for this circuit. Is 'a' just a prefix to multiply...
  13. Athenian

    Young's Photon Interference - Question on Angle & Voltage

    After conducting the photon interference experiment, below is a sample data of what we got: Time (s) Angle (V) Two-slit Diode (V) 0 0.988 0.203 0.102 0.984 0.297 0.805 0.976 0.398 1.201 0.974 0.5014 1.31 0.968 0.526 The above list goes on for quite a few columns...
  14. bardia sepehrnia

    Engineering Calculating Power Factor in an AC circuit, given voltage and current

    My attempt at solving this question: I realized my attempt is wrong however I just don't know how to proceed in the first step. How can I calculate the phase shift? and find Voltage and Current in phasor form??If I know that, then I can use power factor formula: pf=Pav/V*I
  15. PhysicsTest

    Minimum voltage supplied to motor windings

    I have seen the following specifications in the Hurst motor data sheet. i have confusion on the Minimum DC voltage to the motor windings. It says as 10Vdc, but even if i give less than 10V it should not damage the motor windings. I can understand the upper voltage if i cross it may damage the...
  16. Ntip

    Gate driving voltage for GaN MOSFETS

    I am interested in using GaN MOSFETS for my circuit and I'm looking at the EPC2012C. I'll attach the datasheet here. I noticed that it calls for a -4 Vgs. If my driver only goes to 0 V, will this cause a problem? What is the benefit in driving negative if it's not required?
  17. Johnstonator

    Engineering Determining if voltage or current is positive or negative with sources

    So I'm confused on a few things about this circuit. I know my math is right (since I got the absolute values correct), but the signs are off since I can't tell when the voltage, current or if the general power equation is positive or negative. A) So my first question is, where is the current...
  18. X

    Engineering Step response of RC circuit with independent voltage and current sources

    Dear PF, In the figure down below is Q7.47 which asks to determine the voltage v(t) across the capacitor for t > 0. Since it is given that V(0) = 0 there are two scenario's which is between time interval 0 < t < 1 and t > 1 according to the independent sources. For the scenario 0 < t < 1 the...
  19. M

    Transistor base voltage calculation

    Hello, I am trying to find base voltage. In attached picture (using Multisim) there are two separate circuits. Here is how I am doing the voltage divider: Circuit on right: Vb = (Vcc - .7)*R6/(R6 + R5) = 3.2V which matches Multisim result. No problem here. Circuit on left: Vb = (Vcc -...
  20. PhysicsTest

    Is the Solution for Finding Hall Voltage Correct?

    The question is to find the Hall voltage The magnetic field is in the +ve Z-direction, the electric field is in the +ve X-direction, the current will be in -ve Y direction. There are many equations to find the hall voltages ##V_H = Ed=Bvd = \frac{BJd} {\rho w} ##. But i find the equation ##V_H...
  21. waazwag

    Induced voltage difference in a magnetic field

    Hi everyone, I'm currently working on the problem listed above. I'm pretty new to electrodynamics, and I'm learning on my own through a book. I was wondering if someone can please help me through this problem. Here are my thoughts:I think I need to use Faraday's Law of Induction for part (a)...
  22. asd852

    Voltage restriction for nodes on the same branch?

    originally ,I want to prove (TT:current can only flow from c to d),thus I try to figure out what will happen if Vd >Vc,then I label corresponding current direction.Afterwards,I know what's wrong: (A:current doesn't flow out of d ),then I attempted to prove A ,yet I consider that A might not...
  23. J

    Understanding Complex Circuit Configurations

    Having more difficulty understanding the concept, thus I am not showing values. What is causing me confusion is the line in the middle. The first aR and bR are obviously in parallel, but the second aR and bR confuse me. I tried calculating the equivalent resistance from the first aR and bR and...
  24. P

    Engineering Understanding High Entropy Expressions in Circuit Analysis

    Hi I am completely stumped by this question - I have no idea where I am supposed to start with it. I have the answer to part a), which I had no trouble with. Part B confuses me as I am not sure what the frequency of operation is. Would someone be able to help me to understand where to start...
  25. E

    Voltage developed across a cooled crystal

    Here I disagreed with my professor's solution, so I'd like to check with you guys. Each B4+ ion in a perovskite ABO3 structure is displaced by ##0.2 \mathring{A}## parallel to the ##c##-axis w.r.t. the centroid of the unit cell, after the cubic-tetragonal phase transition below the Curie...
  26. propvgvnda

    Find the supply voltage of a ladder circuit

    Find the supply voltage of a ladder circuit shown, so that I=7A. Assume R=11Ω. (The unit must be placed) Hello, everyone. Please, help me with this. Could someone explain to me how to solve such tasks. I literally spent the whole day watching Khan Academy and trying to figure out how to solve...
  27. L

    Maximum Induced Voltage of an AC Generator

    I would like to ask a question about the induced voltage of an AC generator. So, according to a graph I found on Google, the maximum induced voltage is reached when the loop is parallel to the loop. (The graph shown below.) Then I was wondering, what if the loop is initially (when it is at 0...
  28. S

    Using Kirchhoff's Laws to Solve this Circuit with Voltage and Current Sources

    I have defined 5 currents but I can't seem to solve it. I1+1=I2 (left) I5+1=I4 (right) I2+I4=I3 upper node By KVL I have determined that I2 and I4 are equal, but I cannot determine the specific current across each resistor. Thank you for your valuable help.
  29. PhysicsTest

    Why is the Voltage Drop Across a Resistor -Ve to +Ve?

    Really very elementary one, if i refer the circuit below For the source in the direction of current the polarity is -Ve to +Ve that is understood which is conventional current, but in the case of resistance in the direction of current the voltage V_R polarity is -Ve to +Ve. Why for resistance...
  30. cwill53

    Maximum Voltage Between Long Coaxial Cylinders

    At first, I started with the result from an earlier problem regarding the capacitance of a cylindrical capacitor: $$C=\frac{Q}{V}=\frac{2\pi \varepsilon _0\varepsilon _rl}{ln(R_1/R_2)}$$ $$\Rightarrow V=\frac{Qln(R_2/R_1)}{2\pi \varepsilon _0\varepsilon _rl }$$ Then I used the equation...
  31. E

    Voltage across an inductor after flipping a switch

    When the energy of the capacitor is minimal it has no charge therefore the voltage on it is 0. That means that the voltage on the inductor is 0 as well at the moment. The part that confuses me is: why isn't the correct answer 0? How can a voltage change in a single moment? Furthermore I am...
  32. E

    What is the voltage in a parallel circuit?

    Potentials in points E, F, A, B are equal because there is no resistance. In my opinion, losses of potential energy in the resitors R1 and R2 are not equal (potential C ≠ potential G). Then why do we say that voltage in this circuit is the same?
  33. M

    Engineering Voltage pulse sketches for reflection on a lossless transmission line

    Hi, I was recently attempting a question about transmission lines and I don't seem to really understand how the voltages travel through the line. Question: If we send a voltage pulse of amplitude ## V_0 ## through a lossless transmission line, what does the voltage at the output look like when...
  34. Mayan Fung

    I Recombination and open-circuit voltage in solar cells

    From the ideal diode model, we can derive the open-circuit voltage (Voc) as: $$ V_{oc} = \frac{nkT}{q} ln(\frac{I_L}{I_0} + 1) $$ where ##I_0## is the dark saturation current and ##I_L## is the light generated current. From the model, if the recombination rate increases, the dark saturation...
  35. J

    Voltage Clamp and current clamp

    If i was conducting an experiment where i wanted to determine the ion selectivity of an ion channel that has a similar structure to voltage gated Na channel but is different in ion selectivity, would i use a voltage clamp or current clamp to figure this out. Also would i use a cell line or an...
  36. J

    Why are PCB Trace and Layer Spacings Based on Voltage?

    I understand that PCB trace spacing is typically based on a minimum found in certain standards and that is voltage based. If the breakdown strength of the dielectric is based on e-field intensity, wouldn't it be beneficial to actually consider the material properties and make it based on a...
  37. J

    PCB Layout questions for my High Voltage circuit

    I am looking at using a few 2 kV film box capacitors in series and I'm trying to make the board as compact as reliably possible. Let's say that I have two equal valued series capacitors rated for 2 kV each in series across a 4 kV power supply. Each capacitor will then have a voltage at 2 kV...
  38. B

    Electric Potential inside an insulating sphere

    I used the potential at the surface of the sphere for my reference point for computing the potential at a point r < R in the sphere. The potential at the surface of the sphere is ## V(R) = k \frac {Q} {R} ##. To find the potential inside the sphere, I used the Electric field inside of an...
  39. R

    Electrical How to wire an LED switch based on rated voltage and current

    Could someone please help. i need to connect a 12vdc motor which can draw 16 amps to a switch that has an led on it. the led is rated at 3v 20mA. The power supply i am using is rated to put out 12vdc at 30A I thought of the possibility of adding a resistor to the positive pole of the led. In...
  40. D

    Voltage using different references

    The problem is for a solid sphere uniformly charged with Q and radii R. First I calculated taked ##V(\infty)=0##, giving me for : $$ \begin{align*} V(r)=&\frac{3Q}{8\pi\varepsilon_0 R}-\frac{Q}{8\pi\varepsilon_0 R^3}r^2\qquad\text{if $r<R$}\\ V(r)=&\frac{Q}{4\pi\varepsilon_0 r}\quad\text{if...
  41. S

    Electrical Voltage readings in 14-3 Romex connected to combo switch

    In a house (USA) there is "combination switch" ( e.g. https://www.acehardware.com/departments/lighting-and-electrical/switches-outlets-and-plugs/switches/3235199?store=16359 ) containing 2 two-pole switches. [Edit: correction: 2 single pole switches]. The electrical diagram for the circuit...
  42. aspodkfpo

    A blob question and a voltage question from the same physics paper

    For Q13 D) E) F), the model I had built was based on elastic collision with the blobs going out of the box, but colliding with air particles and then going back into the box. Thus, momentum would be redirected and it would be higher than what the answer says and kinetic energy would also be...
  43. Rongeet Banerjee

    How can I find the DC component of an Output Sinusoidal Voltage?

    I had previously solved this using Root Mean Square method by integrating the value of voltage from t=0 to t=T/2 and then from t=T/2 to t=T.Answer was Vo/2½.Yesterday I found this question👇🏾 if I followed the previous approach then: 5 volts is not even in the option. How can I find the DC...
  44. Kaushik

    Understanding the Phase Difference Between Voltage & Current in a Circuit

    Consider a circuit with a witch, capacitor and an AC voltage source. The sinusoidal AC voltage source is depicted in the following graph: We know that, ##Q = CV## ##\frac{dQ}{dt} = C \frac{dV}{dt}## ##i = C\frac{dV}{dt} \tag{1}## So from the graph, the voltage increases rapidly around ## t =...
  45. jisbon

    Calculating Equivalent Voltage in a Complex Circuit: Thevenin vs. Norton

    From this, I can transform the current source to: I can then find the equivalent resistance to be (30//20)//40 = 9.23 ohms. However, I am not sure how to find the equivalent voltage in this case? What should I do to start?
  46. J

    Understanding the base emitter voltage in a common emitter NPN BJT

    ##V_{BE}## is basically the difference in voltage between the base terminal and the emitter terminal. Normally when silicon is used and the transistor is biased to operate in the active region, ##V_{BE}## = 0.7 V approximately. The way I understand this is that for an npn BJT, the applied...
  47. K

    Why is S=2*pi*r*l in the equation for induced voltage of a DC motor?

    Induced voltage of DC motor isV=Blv where B= phi/S where S=2*pi*r*l and magnetic flux is phi=B*2*pi*r*l as shown in the picture. that leads to the equation V=PZ*phi*N/60amy question is, why do we set S=2*pi*r*l Shouldn't magnetic flux 0 because the magnetic flux of a closed surface is 0...
  48. Kaguro

    Engineering What to Do When Input Voltage is Variable? | 5-20mA Range Explained

    This is a very confusing situation for me. If the input voltage were constant, then I would be able to understand that by varying load resistance, I can change the current through it, such that the drop across the load = Vz = 6.8V. But the input voltage is also not constant. So what am I to...
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