Voltage Definition and 1000 Threads

I am trying to derive a scaling factor for an analog voltmeter for the purpose of measuring the secondary voltage of an electronic halogen transformer (EHT). http://www.ledbenchmark.com/faq/Transformers-Output-and-Compatibility.html The output voltage of these things is a "high frequency"...

I'm working on an Arduino project to read automotive battery voltage,.. I could use a simple resistor divider circuit, but I'd lose a lot of resolution (you aren't going to see <8V very often).. Could anyone take a look at this and tell me if it's a reasonable method?.. Channel A (Blue) is...

Hello, if I had salt water and put microscopic spheres with iron spikes in (a lot of them, say 1,000). Then if a high static charge was applied to the water (say 500,000 volts), what would happen? My intuition tells me that the electric field would concentrate on the tips of the spikes, making...

Homework Statement Find Vo Homework Equations KVL, KCL The Attempt at a Solution Mesh equations: -24 + I1(2-j)-I2(1.5j)=0 I2(6+4j)+10<30degrees-I1(1.5j)=0 I1=8.69541+3.59557j I2=-1.00284+2.00908j How would I find Vo?

I know theoretically fuel cell efficiency decreases as temperature increases. But in practice it is vice versa. What is the reason of that? I couldn't find enough sources. Any kind of help is much appreciated.

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.

1. Homework Statement The problem is above, I am having a hard time figuring out why the right answer for part F is "greater than." Homework Equations Ucapacitor = 0.5 * C * V^2 The Attempt at a Solution [/B] My problem is figuring out the logic in how the capacitor's energy would...

Homework Statement I need to find Vc(t) in the following circuit: Homework EquationsThe Attempt at a Solution I was trying to follow an example in my notes. They automatically consider that t>0 it becomes closed and therefore like a short circuit. Can I do that in this case? If I do that...

Hi. There's this nice water circuit model for electric circuits where pressure corresponds to electric potential and the (mass or volume) flow rate to electric current. In the water model, we can vary the pipe diameter along the circuit. Since water is practically incompressible, the flow rate...

Homework Statement We have a resistor grid with 6x6 squres. ( figure below) If we know the voltage between ##O## and ##A##, what is the voltage between: ##a) O## and ##B## ##b) C## and ##D## ##c) E## and ##F## Every side has the same resistance. Attempt for solution: Because of the symmetry...

Homework Statement Above is my attempt of the answer and the problem q. The correct answer is -2V. In the solutions given to us, it has this line: I understand that V- is 0V due to the characterisitcs of an op-amp. But I don't understand where is the - V0 coming from. Any ideas...

Hi. Consider a simple circuit consisting of a voltage source ##U## and a load with resistance ##R##, e.g. a lamp or a motor. The current is given by ##I=U/R##. The number of electrons passing the circuit per second is ##n=I/e##. The power consumed by the load is calculated by $$P=U\cdot...

Hello, If a positive charge is moved from point b to a, then we say a is positive to point b, and assign negative polarity to point b. If a negative charge is moved from a to b, we still say the same. Why? Please explain in simple terms if possible. Another question, if current and voltage...

Homework Statement We just started capacitors in class and we were introduced to the formulae q=CV and i = C*dV/dt In the notes it said that if the voltage across a capacitor were to change instantenously, the capacitor current would be infinite. It goes on to say why this is never possible...

This question comes from the equation E = vB (moving conductor in a magnetic field -- E = electric intensity, v= speed of the conductor's movement, and B = magnetic field strength). Say B is constant, so the only thing we have to rely on to vary the electric intensity in the conductor is its...

In a RC circuit is voltage through a capacitor always consider negative no matter if you're going with or against the current when setting up a voltage equation?

Homework Statement So we just covered op-amps in class and when going through the lecture notes and reading the topic about ideal op amps, I came across this. It says that if the gain A is infinite(which it is in ideal op amps), the only way the output voltage v0 can remain bounded is if the...

Homework Statement When Voltage is oscillating (A/C), then in a simple circle with steady resistance, the current will be proportional to the voltage. When voltage increases, current will increase. And when voltage decreases, voltage will decrease. Is it also true that in a simple circuit...

Hi. In a normal power plug, neutral is on the same potential as the Earth and therefore, in theory, safe to touch. Line carries the full voltage difference and is dangerous if the body provides a conducting connection to the earth, since this closes the circuit to neutral. Isolation...

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 A battery with = 12.0 V and internal resistance r = 1.0 Ω is connected to two 6.9 kΩ resistors in series. An ammeter of internal resistance 0.50 Ω measures the current, and at the same time a voltmeter with internal resistance 10.0 kΩ measures the voltage across one of the...

Homework Statement Suppose you want to run some apparatus that is 95 m from an electric outlet. Each of the wires connecting your apparatus to the 120 V source has a resistance per unit length of 0.0065 Ω/m. If your apparatus draws 2.9 A, what will be the voltage drop across the connecting...

Ok I am having a problem with my furnace in my home so I called a friend that is a certified HVAC technician to come over and help you work on it so upon doing some tests we come to find out that one leg of the 220 had 220 volts and the other leg had 10 what could be causing that

Hi! I have a question about induces volatge and current in an odd scenario. Suppose we have a leader in a homogeneous magnetic field caused by two strong magnets (btw, which causes the strongest magnetic field?). Assume now that a charged ion travels through the magnetic field. It will mean a...

Good Evening/Morning/Afternoon Everyone, Question: Why is it that demonstrations of Van de Graff generators use Leyden Jars in series to get bigger sparks? If a spark gap's size determined by voltage, and Leyden jars are simply to be treated as capacitors which wouldn't increase voltage, why...

Homework Statement Find the V and I in the circuit shown below: Homework Equations D1 or 2 is off=short circuit D1 or 2 is on=open circuit The Attempt at a Solution So, my confusion lies with deciding the on and offs of D1 and D2 . My assumption is that both of them are on and that is due...

Homework Statement Solve this circuit: a) Mark all currents b) Write a system of equations allowing you to solve for the currents2. The attempt at a solution Part a) in attachment. Part b) \epsilon_1 = i_1 r_1 + (i_1 + i_2 + i_3) R \epsilon_2 = i_2 r_2 + (i_1 + i_2 + i_3) R \epsilon_3 =...

Hello everyone, From what i know electrical resistance for metals is a constant, but in fact it varies with temperature but not voltage. Explanation for metals and temperature is something like "heat, which is in fact average speed of electrons, does obstruct tranmission of other electrons...

Homework Statement An elevator is running upwards at the constant speed v. The magnitude of opposing forces is F_o. The elevator's mass is m and the voltage is V Find the magnitude current in the elevator's engine. 2. The attempt at a solution I tried to solve this task by energy equations...

In an open circuit, a voltmeter in parallel to a battery measures the EMF. Once the circuit is closed, the measured voltage drops due to both the internal and the external resistance. My question is how can the initial resistor not affect the voltage the voltmeter measures? Additionally...

Please explain how or why (I have zero knowledge in physics).. 1. is Voltage the energy required by the elctrostatic forces between 2 points to move a certain quantity of charge between them? 2. Why is it called potential difference? Does this have to do with the difference in potential energy...

Homework Statement find the voltage between a and d and terminal of each batteries Homework Equations Junction Rule and Loop Rule The Attempt at a Solution I got three equation JR : I3 = I1+I2 LR : 45-I3-47I3-34I1 = 0 45-I3-47I3+85-I2-18I2 = 0 I can't solve these...

Hi again dear friends. , hope all are doing well. Please could some one evaluate my work and advise me in case any correction is required. Have a good day

I've got two monitors I am trying to power with a battery. They accept 19V @ 1.3A each, and I'll have them in parallel off a single battery, so they'll need 19V @ 2.3A from the battery. I'm looking at http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=56845. The specifications...

if I heat a resistor, it will reach a specific temperature and keep it. because as temperature increases the resistance decreases, so reducing the power absorbed. is that true? and how to calculate how much current and voltage I have to deliver to reach a specific temperature?

Homework Statement Excuse me for the bad drawing: A conductor moving with a speed of 2.5 m/s in an uniform magnetic field (1.2 T) as declared in the picture below. Calculate the voltage induced in the rod. Homework Equations E = vBL W = F d cos[/B]The Attempt at a Solution The resulting...

Hey, I am having problems with this. I need help with these 2 circuits I am basically lost and not sure how to start. I need to find voltage, current and potency on each resistance help would be much appreciated, thank you http://imgur.com/trm1On0 http://imgur.com/a/KD3zr

Homework Statement Use Mesh analysis to find voltage of Node A and B Homework Equations V=IR KVL The Attempt at a Solution Are my mesh equations correct? Mesh1: -j30V + (-j50 + 10)I1 - 10I2 = 0 Mesh2: (10-j20)I2 - 10I1 - j50V - I3(-j20) = 0 Mesh3: (-j20+30+j10)I3 - (-j20)I2 = 0

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) =...

I noticed that I could get a minor belt off my 3 x 1.5KW compressor. I attached my meter to a mains supply 'socket earth', and to 'the chassis'. I watched the AC voltage gradually rise... perhaps increasing in speed slightly as the potential difference increased between the chassis and earth...

Homework Statement a. Find the voltages Va, Vb, and Vc. b. Find the currents I1 and I2. Homework Equations Ohm's Law, Current Divider The Attempt at a Solution [/B] My first attempt was to redraw the circuit. I know that these voltages are with respect to ground. Therefore Va to Ground is...

Hey! I have a question and a drew up a diagram to help out. I drew up a circuit that includes just a voltage source and a resistor. I know the voltage is constant in each of the circled portions of the circuit. As in, as you move through the wiring, the voltage doesn't change from one point to...

Homework Statement Homework Equations Vab = ∫ E*dr The Attempt at a Solution [/B] For part (b) I am not sure if I should set the upper and lower bound of the integral from "R" to "2R" or "2R" to "3R". If done so, this would give me V2R = Vab * ln|3R/2R| / ln |3| instead of what is on the...

Homework Statement [/B]Homework Equations V = IR The Attempt at a Solution I used nodal analysis. Let voltage at central point be Vx So 1) (10 - Vx )/ 2 is current entering from left branch. 2) Current entering junction from middle branch is 4 Vs Vs is current in eqn 1 times 2 ohm . This is...

I started simply looking at a circuit breaker connection diagram, then I fell down the rabbit hole. So I wondered, if you had a piece of pure copper and getting rid of heat (structural integrity, gravity etc.) was not an issue, just how much current could you push through it before it hit it's...

So what's the smplest illustration for voltage ,current and resistance and what's ohms law ?

Hi. I learned that in an ideal conductor in a circuit, the voltage drop is zero. But how does this agree with the basic definition of voltage $$U_{AB}=\int_A^B \vec{E}\cdot d\vec{s}\enspace ?$$ The electric field inside a conductor only vanishes in static conditions, but in an electric circuit...

Hi. If a plate capacitor is charged with some charge ##Q##, then there's a voltage ##U=Q/C## between the plates. The electric field between the plates is ##E=U/d##. Voltage is path independent, if I connect the plates with a cable of length ##l\gg d## the voltage across the cable is the same...

Homework Statement A galvanometer of resistance 40 Ω requires a current of 10 mA to give a full-scale deflection. A shunt is put in position to convert it to a meter reading up to 1.0 A full-scale deflection. A resistance bobbin, intended to convert the galvanometer to one reading up to 1.0 V...

Hi. I need some help in explaining in a simple way how to calculate the minimum allowable frequency at a certain voltage when selecting a pulse transformer. The one I'm looking at has an ET value of 45Vusec. I'm feeding it 22.5KHz at +/-6VAC square wave. It seems to work fine but I fear it is...