Voltage source Definition and 127 Threads

Hi, I found this interesting video about How electricity actually works. The point he makes (see for example the video at minute 7:23) is that the energy in a light bulb connected to a battery is actually transferred by the electromagnetic field and not by electrons flowing through it. The...

Hi. A plate capacitor is connected to a constant voltage source. The stored energy is $$W=\frac{1}{2}\cdot C\cdot U^2=\frac{1}{2}\cdot \varepsilon_0\frac{A}{d}\cdot U^2\propto\frac{1}{d}$$ if the voltage source remains connected when varying ##d##. So the energy decreases with increasing...

##V_{S} = 120V ## ##f = 60Hz## ##L = 20mH## ##R = 10\Omega ## (a) Assume the capacitance is omitted. What is the resistor voltage? ##X_{L} = j\omega L = j2.4\pi## ##V_{R} = Vs\cdot \frac{R}{R+X_{L}} = 76.5067-j57.6847## ##V_{L} = Vs\cdot \frac{X_{L}}{R+X_{L}} = 43.493+j57.6847## (b) What...

As per ohms law the current is generated based on voltage and resistance V=IR. So if 5v and 1k resistor the current 5mA flows in resistor. But if I take a current source, can I pump any amount of current to resistor? So, current drawn is not characteristic of resistor?

Okay so This is what I've tried; a) A formula I've found in the lecture notes; $$ U_a = U_q - R_i*I $$ To get I used the ## I = \frac{P}{U} ## formula I get I to be 0,46 A.Now put back in formula for and rearange to get Ri should be $$ \frac{Ua-Uq}{I} = Ri $$ and the solution should be 0,43...

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Suppose I have a galvanic cell, where I've arbitrarily set the (-) anode to have a potential of zero volts and the (+) cathode to ##\epsilon## V. The electrodes are connected via the load, but also via the solutions and salt bridge in the centre. Edit: The two trailing wires are connected to a...

I need to create a powersupply that takes in a +5 and -5v and has an adjustable output that varies between -2 and +2 v using one potentiometer. I already came up with a design myself but it did not work. I need some help figuring this out. I think my idea for how to get specific positive or...

so when I did this problem I did nodal analysis to find the voltage across the 40k resistor, and found it to be 16V. From there I did two source transformations, combined the sources and did some equivalent resistance to get the answer as seen below: However this differed from the answer he...

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...

I would upload it soon

Homework Statement Find Vx, as the 5A current source provides 50W to the circuit. Homework Equations ##P = V.I## ##U = R.I## The Attempt at a Solution [/B] At first, as 5A current source provides 50W, by ##p=vi## there should be 10v through it. Then, i applied KVL and found four equations...

Homework Statement In addition to the question given in the attached file below, I don’t understand how is the polarity changing periodically. Homework Equations Concept-based question, I guess. The Attempt at a Solution I have no idea how should I approach the question. So, if anyone has an...

In this circuit,first there will be voltage drop in the internal resistance of the voltage source.Mostly,the voltage source is assumed ideal in circuits,however,here a practical voltage source is assumed. So,there will be voltage drop in the internal resistance of the voltage source which will...

Homework Statement Homework EquationsThe Attempt at a Solution I don't understand why would the current be zero in any of the branches . May be I am missing something very fundamental . Please help me understand this question .

Homework Statement http://www.chegg.com/homework-help/questions-and-answers/problem-2-variableh-resistor-r-circuit-fig-p224-adjusted-va-equals-60-v-find-value-r-q8083343 Homework EquationsThe Attempt at a Solution Hi, I attached a pdf file with the problem. My question is, for the lower right...

Homework Statement Select the correct expression for ##i_o(t)## for ##t≥0^+##. Homework Equations ##V(t) = V(∞)+[v(0)-v(∞)]e^{\frac{-(t-t_0}{\tau}}## ##i(t) = C\frac{dV(t)}{dt}## ##\tau = RC## The Attempt at a Solution I'm a bit stuck on this problem. Specifically, I'm not sure how to deal...

Well let me explain. I've finished a circuit that consists in a microcontroller unit (in this case a PIC16F877A) that is connected to a LCD module, a keyboard and a RTC module (via I2C protocol). As far as I know all of them require VCC (=+5V) for operating so I needed to create a +5V regulated...

Homework Statement The current source and voltage source in the circuit shown in the Figure below are connected in parallel so that they both have the same voltage, vs. The current source and voltage source are also connected in series so that they both have the same current, is. Suppose that...

If I have a resistor and a voltage source in series but then I apply a short circuit in parallel to both of them would the voltage source and resistor not receive 0 V? Thus having 0 current. What would change in the circuit?

Homework Statement Here is a diagram of the circuit and my redrawing with currents drawn: We are to find the power delivered by the dependent voltage source. I found a solution online, but I am not sure why they had the KCL line as: $$ \frac{v_1 - 160} {10} + \frac{v_1} {100} + \frac{v_1...

i was reading about CSI and the first paragaph said "A constant current source is assumed here, which may be realized by using an inductance of suitable value, which must be high, in series with the current limited dc voltage source. " and it says nothing else about it , so clearly it's a basic...

Is the work done by a constant voltage source positive or negative when current is opposite to emf?

Homework Statement [/B] Derive an expression for vc(t) in the circuit of Figure P4.13 and sketch vc(t) to scale versus. I attached a screen shot of the circuit for this problem. time. Homework Equations V = IR V = V0exp(-t/tau) The Attempt at a Solution [/B] I am trying to find the...

Homework Statement Two hollow metal spheres (left one has radius of 0.7 meters and right one has radius of 0.4 meters) are half-submerged in the sea water with specific conductance of γ = 4 S/m. Distance between their centers is much greater than their radii dimensions and equals 60 meters...

Homework Statement A voltage source E_0 cos ωt is connected in series with a resistor R and a capacitor C. Write down the differential equation expressing Kirchhoff’s law. Then guess an exponential form for the current, and take the real part of your solution to find the actual current...

Homework Statement Homework EquationsThe Attempt at a Solution (a) [/B]We can assume for ideal op-amps that there is: infinite input impedance low output impedance the potential for infinite amplification (b) Non-inverting op amp (c) This is the part I have trouble with. There is three...

multiple 220V to 5v, 2A ac to dc adapters connected to the same 2-phase input terminals input voltage is 220v domestic supply. is it safe to i join output in series to obtain 10v /15v/25v etc. ?

Homework Statement Vs = 100cos(2000t) Homework Equations KVL, KCL The Attempt at a Solution My mesh equations are: -Vs + I1(30-12.5j)-I2(120j)=0 4Ix+I2(120j+20)-I1(120j)=0 Ix = (I1-I2) Are these correct? When I solve I get a different result than when I do nodal analysis.

Homework Statement Find the: -Complex power delivered by source -Power factor of total load -Is the power factor leading, lagging, or in unity?[/B] Homework Equations KVL/KCL The Attempt at a Solution I want to solve this via mesh analysis to get currents. Mesh1: -10V + V1 + 0.75V1 = 0 V1 =...

Homework Statement Using the superposition principle, determine the current i(t. 2. Homework Equations Zc = 1/jwC Zl = jwL V = I*R I = V/Z The Attempt at a Solution First, I converted inductor/capacitor to impedance: L = 1.5H -> jwL = j * 10 * 1.5 = 15j C = 10mf = 1/(jwC) =...

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...

Homework Statement R1 = 2 ohms R2 = 4 ohms R3 = 6 ohms E1 = 10 V E2 = 14 V What is the voltage between point A and B ? A. 0.18 V B. 0.98 V C. 1.34 V D. 1.64 V E. 3.28 V Homework Equations KVL The Attempt at a Solution [/B] I tried using KVL I assume that both mesh currents will go in...

Homework Statement A real voltage source can be expressed as an ideal voltage source that is in series with a resistor that represents the inner resistance of the voltage source. This voltage source is a EMF and it is also in series with another resistor. Suppose both the EMF resistor...

Power systems isn't my area of specialty and I've been doing some reading where it was stated that series voltage connections are safer than parallel connection. I don't fully understand why though. website address...

This isn't actually a homework problem, but it is an example in a my textbook that I have a question about... imgur link: http://i.imgur.com/2OglMH4.png Ok, I wanted to clarify some things. I understand that current flowing from a positive terminal to a negative terminal represents a...

Homework Statement In attached image. Just curious as to how their nodal analysis is correct. Homework Equations [/B] ##I_{in} = I_{out}## The Attempt at a Solution Solution in image. I am just not sure how they applied nodal analysis here to find that ##I_s = \frac{12}{12} +...

Normally, I would just assume that for a circuit with just a dependent source, I can treat it the same as as one with an independent source. Using Picture 1 Assume that I want to find the Thevenin wrt nodes A and B. I want to find Rth, so I zero out all sources, which makes I = 0A. The only...

Homework Statement Use nodal analysis to calculate Va, Vb, and the currents IE1 and IE2 without using source conversions I have tried this many, many times, and I must be missing somethingHomework Equations [/B] The equations I came up with: VA-10/ 1.1 + VA/1.2 +VA-VB/1.4 = 0 VB+2/1.5 +...

Homework Statement http://www.sumopaint.com/images/temp/xzkaelnnkibopbdq.png The electric current that goes through the 5 ohm resistor is A. 0 A B. 0,3 A C. 0,6 A D. 0,9 A E. 1,2 A Homework Equations 1/Rparallel = 1/R1+1/R2+... Rseries = R1+R2+... The Attempt at a Solution I take the 6...

Homework Statement Given a series RLC circuit, with one R, one L, and one C element, and an AC voltage source with variable frequency, find the resonant frequency experimentally given an ammeter and a voltmeter. Homework Equations The current in the circuit when the circuit is in resonance is...

Hello, I'm currently working on a problem involving the calculation of an unknown voltage source of a circuit containing a resistor, inductor and load in series. Unfortunately, the problem sheet does not give an answer at the end, so I am unsure as to whether my approach is correct -- hence...

Homework Statement Homework Equations V(oc) = I(sc) * R(th) Kirchoff's voltage law The Attempt at a Solution a) is okay. For part b): After redrawing with the R(th) and V(th) found in part a): Equations of loops: s is I(sc) a is I(left loop) left loop: -8 + a(4000) + (a-s)(4000) = 0 right...

We are doing an experiment to verify coulomb's law, and we are currently using a stable voltage source. However, we were assigned to do it using static electricity, and we were wondering how to establish inverse r^2 dependence if the amount of the charge on the ball isn't the same every time we...

If we connect a single resistor in the circuit of ideal voltage source then what'll be its total resistance? ? Isn't it zero? As shown in image .so is it possible that the total resistance of a circuit is 0 Although it has 5ohm resistor!?

Homework Statement This diode zener has breakdown voltage equal to Vz=8.2V for currents: 75mA<=iz<=1A.If RL=9 Ω,how much must Rs be,so that VL=Vz=8.2V,while Vb changes at about _+10% in relation with the nomimal operating current,displayed in the data sheet which is 12V? The Attempt at a...

Homework Statement http://i62.tinypic.com/245fwxu.jpg[/B]Homework Equations & Attempt to solve [/B] http://i62.tinypic.com/142v6mv.jpg Bottom: A Top left: B Top Right: C(1/100 + 1/5 + 1/25)VB - (1/25)VC + 6.25I = 450 mA (20.8)VB - 0.04 VC + 6.25I = .450 A VC = 45 + 6.25I I know I'm doing...

Homework Statement Find V0 using voltage/current division Homework Equations V=(VsR)/Req I=(IsIeq)/I The Attempt at a Solution I used general circuit rules (parallel and series) to get the total resistance as 14.775 ohms{?}. And I'm stuck with what to do next . . .

The question is to solve the current through a resistor after a pn junction. (photo attached) As far as I'm aware the voltage source in the pn junction is (in this orientation) of opposite polarity to that of the 0.8V voltage source. From my understanding the answer goes like: V=IR I=V/R...

Hello guys.I am really having a problem with a circuit that includes a dc source,an ac source,2 resistances and a diode(not ideal).In the pdf that i uploaded is my way of thinking for this.I will really value any help and guidance. Thnx in advance