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).
Homework Statement
1. Use resistors of 30 ohms, 40 ohms, 50 ohms, and 50 ohms to create a circuit with a total resistance of 95 ohms.
2. Find the amount of current going through two of these resistors if the circuit is attached to a source of 12 v.
3. What would be the voltage drops for the...
Can someone please tell/explain to me how voltage affects electrons. Does it determine the speed of the electrons in a conductor? Is so why a power supply rated 12v 3A and another rated 9v 3A have the same amount of electrons traveling at the same speed through the conductor. My big question is...
Homework Statement
Question: A cathode ray tube in a TV has an electron gun operating at 10 kV.
a: What is the velocity (in m.s-1) at which the electrons are emitted? Answer:5.9x107
b: How many volts are needed between the deflector plates to move the beam impact spot across a 70 cm screen if...
In the experiment of the determination of ##h## using the photoelectric effect produced by light emitted by led's there is the systematic problem of the "dark current" or "back current", i.e. the current caused by photoelectric effect on the anode of the system which is used in the expreriment...
Homework Statement
In the figure below find V(o) / V(s)
Homework Equations
In an opamp current doesn't enter through the inverting and non-inverting terminals, furthermore in DC conditions a capacitor acts like an open circuit
The Attempt at a Solution
The way I see it, both capacitors will...
Homework Statement
I would like to know the initial voltage across the capacitor terminals in the following diagram.
Homework Equations
when a capacitor is connected to a DC source for a long time, it acts an open circuit.
The Attempt at a Solution
for t < 0, we get the diagram below and I...
Homework Statement
An inductor (Xl = 40.2 ohm) is connected in series with a resistance (30 ohm) and and an AC source ( 10V , 80Hz) and the current flows in this circuit is 0.2 amp. How could you reduce the phase difference between current and voltage to zero without changing the value of...
Hey Guys, so I'm just in need of some help in relation to finding the output current after the voltage has been dropped to 6V. The circuit has an input voltage of 24V and I've attached a photo of my circuit diagram. Hopefully I haven't made any errors in that, but I've tested the circuit and it...
Hello,
I am having a hard time deciding the size of a solar array to boil water for a school project. Before putting any thought into the subject I simply thought that I would just take the wattage of the panels and add them up since they are added in both series or parallel and then select an...
I'm looking to draw about 6A. I have an LM338 regulator that can supply up to 5A. Searching the internet I came across this schematic,
So basically when the 1R resistor drops 0.6V then the transistor conducts the remainder of the current. I calculated my own values for those two resistors. Was...
I have a lab to work through tomorrow morning and i need to be able to explain how the voltage, current and resistance in the compound circuit diagram below is distributed, and write an equation which can be used to measure the total resistance of the circuit. I know that when you normally try...
Homework Statement
An ac series circuit consists of a voltage source of frequency f = 60 Hz and voltage amplitude V, a resistor of resistance R = 163 ohms and a capacitor of capacitance C = 6.2x10^-6 F. What must the source voltage amplitude V be for the average electrical power consumed in...
Homework Statement
I'm trying to find the output voltage ripple of a buck converter by using just the waveforms and the inductor ripple.
Homework Equations
[/B]
I know that the answer is supposed to be D(1-D)Vin/(16*L*C*f^2) but I keep getting D(1-D)Vin/(8*L*C*f^2)The equations I end up...
I was reading this paper on rectifying properties of mangese oxide films, and came across this mention of diffusion voltage. Can anyone explain please what it is? Here's the context:
In this piece of work, we successfully constructed heterojunctions by growing a manganite...
Hi,
Does anyone know of any fluid that emits light when current is running through it?
Why?
To feed to a flower, apply low voltage and make it glow.
Florescent light isn't enough and bioluminescence isn't my area of expertise so turning a flower into a LED is going to be my approach.
All tips...
Hello,
I have a question about electric elements and their corresponding voltages. I am looking at powering a 1500W 120VAC element out of an ordinary kettle with a DC voltage supplied by solar panels.
So, from what I understand, 120VAC represents the RMS voltage meaning that it would require...
Homework Statement
The X-ray intensity distribution function for an X-ray lamp is
given on the figure. What is the maximum velocity of the electrons? What is the potential difference under which the lamp is operating? Figure: http://imgur.com/01kCBc8
Homework Equations
Kmax = 0.5m(vmax)^2...
The text in the paper says that C1 has Vout/N-1 = Vout/6, C2 has 2*Vout/6 and so on...
Can someone please explain how?
Source : Liao, Zitao, Yutian Lei, and Robert CN Pilawa-Podgurski. "A GaN-based flying-capacitor multilevel boost converter for high step-up conversion." Energy Conversion...
Hi, we know that the speed varies inversely with the torque. The more the torque, the lower the speed. From torque-speed curve, we can calculate the slope. When the applied voltage increases, the straight line shifts upward while when the voltage decreases, the straight line shifts down. How...
Homework Statement
Homework Equations
C = Q/V
The Attempt at a Solution
I understand that capacitors in parallel have the same voltage, but wouldn't they be in series after the switch is flipped, since no current goes to the left most portion of the circuit.
Homework Statement
Calculate the voltage U.
The voltmeter gives a value of 80V.
The Attempt at a Solution
[/B]
3RI + 4RI - U = -80
How can I create a System of Linear equations if I have only one equation?
Do I miss something?
My answer sheet says U = 150V.
Hello,
I was wondering if there is any way of increasing a transistor or thyristor maximum voltage ratting in DC?
Thanks.
Edit: Just to be more precise, I am referring to the off state. I know you can the on state via a resistor.
Homework Statement
I have a problem where I need to calculate vo (i.e. output noise) and VO (i.e. DC output voltage) different resistances in a circuit with a Zener diode. The diode is reversed biased but I don't know the Vz. I have the IV curve but can't seem to wrap my head around how to...
Voltdrop calculations are made as shown below.
Total loadLine currentI=1.5/−60∘⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯+2.3/−18∘⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
=(0.75−j1.3)+(2.19−j0.71) <<< (How to get to these numbers only from above??)
=(2.94−j2.01
)=3.56/−34.4∘⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯MVA
i've been reading on plasma physics and i have a couple of questions.
how to calculate how much volts needed to create plasma with distance x from the electrodes of a certain gas with certain pressure?
and to increase the distance do i have to increase voltage or once i have an arc or plasma in...
Hi,
I want to calculate voltage regulation of a transfromer. I have learned that voltage regulation is (Vnl-Vfl)/Vfl.
While solving some problems for practice I came across multiple questions. In some of them where the load is given I understand how to solve them. I just find the No load...
I have a question that I believe requires knowledge on the graduate level, but I can't necessarily express it in terms more complicated than plain English. If this is not so, moderator, please adjust to your taste, and thank you!
If it helps to know this, I'm an audio/video systems designer and...
Homework Statement
Determine the voltage drop and current through each resistor.
*This is just my sketch of the problem since I couldn't take a clear picture of it.
Homework Equations
Ohm's law
V= IR
Parallel total resistance
Req=1/R1+1/R2+1/R3+...
Series total resistance
Req=R1+R2+R3+...
I want to build own circuit usinghttps://ez.analog.com/external-link.jspa?url=http%3A%2F%2Fwww.kynix.com%2FProduct%2FCate%2F470.htmland resistors. I have 12V power source (car accumulator) and 6V input voltage (Vin). I want to get 12V Vout and 25W at the output. So that is about 2A...
Hi,
The Circuit I am referring to is a simple series circuit with the resistance of the wire is negligible.
I am confused about the fact that if we increase the resistance of a resistor in a circuit, the PD across the component will also increase. From my understanding I thought increasing the...
In this project, I am using the https://www.amazon.com/dp/B005W09XYW/?tag=pfamazon01-20
as a power supply, but in my project, if my device shuts off suddenly without shutting off properly, it would require me to reboot the entire system as it won't work anymore.
So I decided to use this power...
For the B) part, I don't get why is it that for calculating voltage between collector an the emitter (Vce) I take into account diode on base (0.7V), whereas for part A) it's ignored?
Why is Vce in part A and part B are calculated differently? Why is it that in part A voltage of 0.7V isn't taken...
Hello,
I was trying to check with a voltage tester if there was voltage in a light bulb socket (Edison type, no bulb present). Explosion happened (a relatively loud sound) and the safety circuit switch turned off.
My question is, how can one explain this with the laws of physics and how can...
Hello everyone
Im new on the forum and I just discovered what are sync machines...
I have really basic question what I still cannot figure out.. I did some experiments with motor for different field currents and torques. In the result I measured armature currents and did V curves. But next...
Homework Statement
Homework Equations / 3. The Attempt at a Solution [/B]
Here is my attempt at the homework, I'm trying to correct my mistakes and am looking for help in the right direction.
Homework Statement
A capacitor (A) of capacitance 4.0uF is charged to a potential difference of 20V. An uncharged capacior (B) is connected in parallel to capacitor A. What is:
(a) the initial energy stored on capacitor A
(b) the p.d. across A after B has been connected
(c) the final energy...
Homework Statement
Homework EquationsThe Attempt at a Solution
We have been given this question along with some parameters.
It asks for find drain votltage, my question is why isn't the drain voltage just equal to 1.8? I mean the resistor should be getting the entire 1.8V so?
When winding a coil around a magnetic core, if you wanted to tap the coil such that each half has the same AC voltage output, would you:
A) wind each part at the same RPM for the same amount of time, to get the same number of turns for each, or
B) wind the second part proportionally less, to...
I'm having trouble understanding circuits, particularly voltage. So my question is more of a conceptual dilemma. Please correct my definitions and relations if it is incorrect. Voltage is the energy provided per charge, and this energy is converted to KE once the circuit is closed, or in other...
Hello~all,thanks for taking time to read my thread. I'm in hot water now,Can anybody here help me out?
Please look at the following picture,I would like to rise the voltage from 24V to 36V. And I did it according to the datasheet of CS5173. However,the chip always burned out ! I can’t understand...
1. I thought that when switch was closed, voltage at the right side of switch was 0 and long time after the switch is open, the voltage at the right side of the switch becomes 0.
2. After the switch is open ecause of the inductor, voltage at the right side of the switch is εL = induced emf
So...
is= 1.2 mA
i submitted my solution but it was wrong,can someone please explain why?
/* i just wanted to check if my solution is correct so i don't lose marks on my homework
did i do any mistakes ?
if so please explain.*/
my solution:
In the following video:
I understand how the Faraday Cage works, but what has me confused is the arching. If charge is building up on the sphere and then arching over to the cage, where then is that charge sunk to? You would think it would stop arching when there was sufficient charge on the...
Hey guys!
So I'm trying to do this pretty wide diameter in-runner engine, where the rotor is hollow (essentially trying to make a short tube within a short tube :D). After checking out the details between the different types of electric motors (and realizing that I can barely find any...
Why does capacitor charges up to full voltage as the emf of the battery even if there is a resistor is connected in series? I know that having a resistor means it will take longer to charge the capacitor but shouldn't some energy need to be lost in the resistor as well?