Voltage, electric potential difference, electromotive force (emf), electric pressure or electric tension is the difference in electric potential between two points, which (in a static electric field) is defined as the work needed per unit of charge to move a test charge between the two points. In the International System of Units, the derived unit for voltage (potential difference) is named volt. In SI units, work per unit charge is expressed as joules per coulomb, where 1 volt = 1 joule (of work) per 1 coulomb (of charge). The old SI definition for volt used power and current; starting in 1990, the quantum Hall and Josephson effect were used, and recently (2019) fundamental physical constants have been introduced for the definition of all SI units and derived units. Voltage or electric potential difference is denoted symbolically by ∆V, simplified V, or U, for instance in the context of Ohm's or Kirchhoff's circuit laws.
Electric potential differences between points can be caused physically by electric charge build up or imbalance (eg. well known "static" and electronic capacitor) also by electric current through a magnetic field, and by time-varying magnetic fields (eg. dynamo or generator), or some combination of these three. Additionally on a macroscopic scale potential difference can be caused by electrochemical processes (cells and batteries) and pressure induced piezoelectric effect and heat induced emf across metal junctions. These latter processes at microscopic level have the physical origins previously mentioned. A voltmeter can be used to measure the voltage (or potential difference) between two points in a system; often a common reference potential such as the ground of the system is used as one of the points. A voltage may represent either a source of energy (electromotive force) or lost, used, or stored energy (potential drop).
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...
So I've done part a)
Primary current = 200000/415=481.9
Cos θ = -0.8
Sin θ = 0.6
Reg=(481.9 ( 0.014*-0.8 + 0.057*0.6))/415
= 0.0267
Reg% = 2.67%
Part b I simply used the same equation but for secondary:
@ unity p.f., cos θ =1, sin θ = 0
secondary current = 200000/11000 = 18.18...
Hi,I have found in my textbook the formulas for both current and voltage and I have no idea if they are right or wrong. Can someone help me with these formulas?
v=v0cos(wt)
i=i0cos(wt)
Is this correct? In google when I search for the answers I get something else:
v=v0sin(wt)
i=i0sin(wt)
Preface: I am new to physics and am trying to learn on my own, though I hope to take a class soon. I looked for a forum for beginners but didn't see one, but this seemed to be the closest forum. So I hope I can get some help with my question here. If it is the wrong forum, feel free to...
To determine the voltage I did voltage/number of globes:
24/16 = 1.5V per globe
- Not sure if this is correct or not
To determine current, I figured out using resistance formulas that the resistance for each set of 8 globes is 15 ohms
R = V/I
24/3.2 = 7.5 ohms total resistance
7.5-1 = 2 * 15-1...
Summary says it all, I think. If you just want to link me to a bunch of papers, that's fine by me.
All I was able to find out on my own is that mouser and digikey have a lot of off-the-shelf voltage references they want to sell me that get about order of ##10^4## SNR at those timescales. SNR...
Imagine the two terminal of a *parallel-plate capacitor* are connected to the two terminal of a battery with electric potential difference #V#. If the capacitance of the capacitor is #C#, and the area of each plate is $A$. In this process would the energy lost by the battery and the stored...
What I already know
In general, power gain is desirable for an oscillator in order to make up for the losses and then feedback that gain (amplified signal) into the oscillator for it to keep oscillating. Voltage gain is not generally used for oscillators.
What I want to know
Since power gain is...
Suppose we have specific amount of hydrogen gas enclosed inside a metallic chamber and that is connected to a very high positive voltage source. As the voltage is positive and that's so high that all the molecules inside the chamber lost their electrons and there is nothing but a nuclei gas is...
If I connect a voltmeter with the positive terminal of a battery and leave the other wire hanging in the air, it won't measure anything since it's not a closed circuit. But if there was a way to measure the voltage between those two points, what would the voltage be? Or is this a meaningless...
I have been studying electronical circuit. In general, it is not difficult and is more about to solve EDO. The main problem is, really, the signs.
See as follows:
$$V_{L} = L dI/dt, V_{c} = +- Q/C$$ ?
Should i put a minus sign there? Or shout i maintain the signs? When do i know what sign to...
The answer is B.
My question:
(a) What is the basic approach to start to think about this problem: Equivalent resistance? ohm's law?
(b) What is the purpose of gamma = R2/(R1+R3) because I have no idea how it uses?
(c) Why the answer is an exponential drop of voltage?
I understand phase voltage (phase to neutral) well, but I'm still confused by what exactly the potential difference is between any 2 phases in 3 phase power. If you were to try to find the potential difference where 2 sine wave phases cross, then at that instantaneous point, the potential...
Hi
Normally our electrical equipment systems neutral to Earth voltage showing 1.4 to 2 volts AC.
Our requirement neutral to Earth is 0 volts.
How to achieve this value ,please help me.
What is the normal acceptable voltage of neutral to earth.
hello,
I did the simulation for the voltage multiplier in Vspace and I want to calculate the efficiency but the OUTPUT POWER is always negative. Do I need help?
can I calculate the power losses of this sextupler voltage multiplier or it is very complicate to calculate it ?
Hi
i want to know just how to approach this question.
i know the omega=100 then should i find XL and XC? and then find the voltage in points c and d?
also how do i find the current that enters point c?
thanks a lot.
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Need help verifying if this circuit design and use of elements is correct. The goal here is to run a 3v motor, hence I need to make the use of voltage regulators for a constant 3v energy to transfer.
Hi guys ! I am taking phys102 course .I figured out that i didnt fully understand the concept that is the Voltage. Please look at this question. In this case we can see that there is no voltage in point C and there is no electric field is in point D and as you know V=U/q .So i always thought...
I need help with part (a)... I know that the root-mean-square voltage is the dc-equivalent voltage for an AC waveform and what my book labels "##V_{dc}## is actually the average voltage. Hence I am assuming the question is asking me to find ##V_{rms}## ...
Is my assumption that the...
Hi!
I'm trying to understand the dependence of spin hall voltage on various parameters of the material. I have been going through this paper, and it is mentioned that $$V_{SH} = 2 \pi R_s L j_x n \mu_B$$
In the equation, only ##L## and ##j_x## seem to be the variables. Does increasing ##L##...
Hello guys!
I am a student who currently works on a project based on electrical detection and voltage measurement in electrical cables remotly. So in order to accomplish my work, I'm seeki ng for new ways to detect voltage. I already have some ideas such as using magnetic fields or measuring...
I've attached pictures with the circuit and part of the attempted solution. I've replaced the diode with its offset model and obtained the equivalent circuit in the 2nd picture. After applying KVL, I've obtained that u_l=−u_D−i_D*R. Since U_D0 is greater than 0, I've deduced that the diode must...
https://www.physicsforums.com/attachments/6-png.282284/?hash=0362cb24c9a8ed9b3ee9efab56a28e3d
If the increasing frequency leads the current amplitude to increases, then Z decreases because V = I*Z and V remains unchanged...
So i want to make a Stage Three: Two Stage Amplifier with Voltage Derived - Parallel Applied Feedback and a Stage Two: Two Stage Amplifier with Voltage Derived - Series Applied Feedback
But am not sure how to layout it out correctly because i have never done this before so i layout'ed it out...
Below is the really quick derivation for average voltage. However when we do the anti-derivative a factor of ##1/\omega## should come out and the full answer should be ##\frac{2V_p}{\pi \omega}##. So why don't we include that? What's going on?
Hello ,so am trying to find a phase shift between voltage and current ,I've done
what do i do after that ?and is this right ?
Q
A 100Ω load is connected to a power supply of 100V at 50Hz. At time, = 0, the instantaneous value for voltage across the load was zero and the current through the load...
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
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...
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...
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...
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...
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...
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
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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...
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...
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...
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...
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...
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
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...
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?
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...