Voltage is the unit of measurement for electronic potential, from one point location to another.

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Resistor and voltage

Considering this simple circuit : The potential is supposed to be constant along each wire (because they're conductors), such that the left wire in its entirety is at the same potential as the ...
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141 views

Why is the voltage of a battery equal to the emf?

We know that there is an electric field inside the battery that works against the moving electrons of a circuit. But there is also the chemical force of the battery that at some point become equal. ...
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44 views

Why is cap voltage negative in KVL for discharge circuit?

I was just trying to derive the equation for a capacitor discharging through a resistor, and I've run into in a problem. If I set up my KVL, then I would say $iR = V_c$ (where $i$ is instantaneous ...
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64 views

how does V divided by EMF shows efficiency

I get that emf = energy per coulomb supplied and that V= energy per coulomb used but i dont get what it means when is says "how"
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76 views

Is it correct to use $P=\large\frac{V^2}{R}$ for AC circuits?

In one of my old notebooks, I found a problem which was basically about finding out resistance of a 100W light bulb (In my country electricity voltage is 220V). Then our teacher had used the equation ...
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1answer
55 views

Different voltages between same point?

In this circuit, we determine that the emf needs to be reversed and that its value is 108.75 V. My confusion is that I thought the voltage between any two points must be the same irrespective of the ...
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20 views

Average induction voltage

I've got a basic question on the method of computing the average induction voltage. Here is the task: A conductor loop with the area $A_1 = 50\text{cm}^2$ in a magnetic field with the flux density of ...
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27 views

Plotting the Graph of $1/I$ on the Y axis against R What does this represent? [duplicate]

What does the gradient, the intercepts represent, what is the equation of my line, and how do I use this information to calculate emf?
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46 views

Multimeter reading between wire & air

Why does a multimeter show 10-20 V(AC) when I connect one of its cables to the hot wire of a 220 V(AC) plug while the other cable is in the air? Also why does this not happen with a 5 V battery? (It ...
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49 views

The affect of high frequency and high voltage AC on induction

I am designing an induction system to wirelessly transfer power a short distance. I was planning on using resonant inductive coupling to increase the efficiency. The Inductance of my coil is about ...
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1answer
54 views

Finding the current and voltage in a circuit with DC sources

I know that in a circuit with DC sources a capacitor(steady state) can be replaced with an open circuit and an inductor(steady state) can be replaced with a short circuit. My understanding is that ...
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44 views

Why does potential drop exist?

I'm sorry that the question is likely to sound stupid but I just can't seem to be able to wrap my head around it. I think I am a bit comfortable with the mathematical idea of it but I still can't ...
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1answer
55 views

Difference of potential between points [closed]

I have the following question: What is the potential difference between point A - B? Could somebody please explain me how should I count it? The voltage U=18V. I found out that V1=8V, V2=10V, ...
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107 views

Why can't I connection the anode of a battery to the cathode of an other battery and get a current flowing?

If I touch the anode of a battery or connect the anode the the cathode of an other battery, none (or rather: a very small current) flows between those two. If I instead connect the connect the anode ...
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0answers
44 views

Does voltage depends on the charge present in an element?

Does the voltage depend on the charge present in a battery ? I know in capacitors q=cv. Hence charge present is proportional to voltage. Is it the same in the case of batteries?
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68 views

Potential difference and voltage

Is potential difference between two points the voltage? (or) Is voltage the potential difference between two points? (or) Are they both the same?
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1answer
29 views

Accelerating an electron to a high speed

Suppose there are two vertical metal plates. They are separated apart by a small distance. While one is grounded, the other one has a potential of some $V$. Now suppose electrons are produced at the ...
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1answer
46 views

In a circuit, if voltage is established at both terminals, then how can components use up this voltage? [duplicate]

Suppose we use a 9V battery. Then the voltage between these two terminals is 9V. In other words, it would take 9 J of energy to move +1C of charge from the (+) to the (-) terminal by the electric ...
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1answer
47 views

What happens if connect 2 points with different potential?

I have a very basic question on charge distribution in electric circuits. Let's say we have 2 independent circuits. If we connect a point with higher potential in one circuit to a point with a lower ...
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1answer
22 views

Non-zero potential measured on the surface of an insulator

After driving a screw into an alumina firebrick and applying a 5kV potential, I measured a ~4.5kV potential using a high voltage probe at other locations on the brick surface. Firebrick is generally ...
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1answer
34 views

Electrical network of current sources - What happens if one source is defect?

Suppose you have connected in a parallel circuit a pair of, say for the sake of concretness 5 sources of 300 mA and 0,5 V each, which are themselves connected together in series. Hence, in total one ...
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1answer
102 views

Why does a non-contact voltage detector light up when you touch a plasma ball with the other hand?

I am doing a science experiment and we decided to try holding a non-contact voltage detector up to plasma ball. We were surprised that it would light up when it was 3 ft away from the plasma ball. I ...
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3answers
64 views

Electric warning signs question

I've always wandered why do the warning signs show the voltage, not the current. I mean, it's the current that kills you.
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If we connect a long wire to a battery, will battery produce more electrons?

I actually have three related questions: An open circuit chemical cell separates charges creating a surplus of electrons on its negative terminus and a shortage of electrons on its positive terminus. ...
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1answer
153 views

Magnetic Wire Doesn't conduct Electricity

I recently bought a 22 and 30 gauge loop of magnetic wire from radio-shack. The loops of wire were colored differently (if this makes any difference) and on the package it noted how these wires were ...
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6answers
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Could someone intuitively explain to me Ohm's law?

Could someone intuitively explain to me Ohm's law? I understand what voltage is and how it is the electric potential energy and that it is the integral of the electric field strength etc. I also ...
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211 views

Capacitance and voltage drops

Let's say that Switch $S$ is closed. I have a conceptual question: If a stream of particles acquire a potential difference upon exiting the battery, why will they lose some of that potential ...
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1answer
69 views

Spherical Magnet Inside a Solenoid

When passing a bar magnet through a long solenoid why is it that the induced emf when the magnet is in the middle of the solenoid is zero? And if a spherical magnet is put inside the solenoid, will ...
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1answer
119 views

Measured voltage on coil

I have a simple circuit of coil with inductance L $$u_c(t)= -L\frac{di}{dt}$$ and AC source with output voltage $u_s$ What is actually measured by the voltmeter ($u_c$, $u_s$ or $u_s - u_c$)? If ...
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1answer
30 views

Showing $\frac{\delta V_{out}}{V_{out}}=\frac{\delta R_2}{R_2} \frac{R_1}{R_1+R_2}$ [closed]

Consider a voltage divider with $V_{out}=V_{in} \frac{R_2}{R_1+R_2}$. Show that for a small change in $R_2$, the voltage divider equation is: $\frac{\delta V_{out}}{V_{out}}=\frac{\delta R_2}{R_2} ...
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327 views

Relation between Power, Voltage and Current when one or more of them is amplified?

Power(P) = Voltage(V) * Current(I) If voltage or current is amplified or multiplied what happens to power and current. Does this affect in increase or decrease in power and current values or does ...
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0answers
46 views

Li-ion Battery charging

Why are constant current mode and constant voltage mode needed when charging Li-ion batteries? Why do we apply saturation charge even after the cell voltage reaches 4.2V? What exactly is 'I-sense' in ...
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354 views

Defining Reference Directions for Voltage and Power (sign convention)

My professor decided to use the above reference directions when calculating power in circuits. He says that when power > 0, power is consumed. When p < 0, power is generated. This definition is ...
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345 views

Why Voltage Drop is not Influenced by Resistor Value?

To my understanding, if a resistor reduces the potential energy of the current across it, then the current that leaves the resistor will have less potential energy and thus, less pressure or voltage. ...
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4answers
184 views

Ohm's Law Question?

Since $V=IR$, if you were to have say a $5\:\mathrm{V}$ source connected directly to ground, no components in the circuit at all, you would need to add resistance for the current to flow? Or is there ...
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1answer
47 views

What is the equivalent of the “amount of fuel” for a battery?

I am trying to make a performance diagram of an electrical powered device vs range, speed, etc. I want to compare it using the equivalent of fuel for a battery? I am not sure if it is just voltage... ...
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201 views

Both plates of capacitor have positive voltage

If both the plates of a capacitor are connected to positive voltage (say, one is +10V and the other is +5V), but there is a voltage difference between the plates, will the capacitor be charged? And ...
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399 views

Why Two Equal Resistors Cut Voltage in Half?

I've been reading several books on electronics, one of them called "Electronics All-In-One For Dummies - D. Lowe (Wiley, 2012) BBS". It states that if two resistors of the same value, no matter the ...
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1answer
58 views

Why there's any voltage on P-N junction in diodes?

If all electrons here have their counterparts in protons, on both, P and N sides, then why there's any voltage (built-in voltage, on the bottom of the image)? Both sides should be neutral, shouldn't ...
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1answer
93 views

A falling steel beam - Maximum induced voltage [closed]

I'd appreciate it if someone could explain how to answer this question: A 2 m long steel beam is falling from a height of 12,5 m. During the fall, the beam is oriented in an east-west direction. ...
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1answer
197 views

Transformers - Why more coils in second coil causes more voltage [duplicate]

I am learning about magnetic induction and transformers. I have coil1 which uses AC to create an oscillating magnetic field. I have ...
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1answer
106 views

Deriving Voltage from Electric Field

I'm trying to derive the point charge equation for voltage by integrating the point charge equation for an electric field over distance ($dr$) traversed:$ \int (KQ/r^2)\cdot dr$ This is my ...
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0answers
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Why does electrolysis require a base electrolyte instead of an acid electrolyte?

I am in the process of using electrolysis to remove rust from some old tools. This is the process where you submerge the rusted item in a bath along with a sacrificial piece of metal. You connect a ...
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1answer
39 views

When do I use the various power-related equations? [closed]

Can someone please tell me when it is appropriate to use the equations $P=IV$, $P=I^2R$ and $P=V^2/R$?
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Current lagging voltage by more then 90 degrees

According to Wikipedia https://en.wikipedia.org/wiki/Leading_and_lagging_current An alternating current that reaches its maximum up to 90° behind the voltage producing it is said to be lagging. and ...
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1answer
89 views

Comparing voltages of Parallel and Series circuits

There are two electric circuits. Resistor 1 ($R_1$) connected with resistor 2 ($R_2$) by series circuit $R_1$ connected with $R_2$ in parallel Each of the circuit has battery with emf and the ...
3
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1answer
258 views

What is fatal? Current or voltage? [duplicate]

I have been searching this answer for quite a while. I asked my physics teacher and he said it is current that causes death. A friend of mine, who is a EE student, and his answer was voltage. When i ...
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353 views

Why can't unequal current sources be connected in series?

Imagine two power sources: PS-1 that can supply $5A$ at $100V$, and PS-2 can supply $10A$ at $40V$. Due to conservation of charge and Kirchoff's current law (KCL), this is incorrect, and would lead ...
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3answers
467 views

Why does my measured I-V curve for a film of aluminum suggest high resistance?

I plotted the I-V curve between two points (few microns apart) on a thin aluminum film. I expected this metal to be a conductor and have a much lower resistance, but the slope suggests that it is ...
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2answers
38 views

Power in a circuit why is V constant

In deriving the power of a circuit we can do the following: $$\text{P}=\frac{dw}{dt}=\frac{dQ}{dt}\frac{dw}{dQ}=\text{IV}$$ But this assumes that $V$ (since $w=VQ$) is a constant. Why can we assume ...