# Questions tagged [voltage]

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

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### At an atomic level, what happens when you connect two batteries in series so that their voltages are added?

I can't for the life of me figure this out. I feel like i'm missing some crucial detail about how batteries work. Imagine two batteries connected in series, like this: ...
3k views

### Measuring voltage drop from induced current

I'm having trouble connecting voltage drops and induced current. Imagine you have a triangular loop make up off three resistors. You place this loop in a constantly changing magnetic field. This ...
116k views

### How does one prove that Energy = Voltage x Charge?

We know $$E = q V$$ where $E$ is the energy (in Joules), $V$ is the potential difference (in Volts), and $q$ is the charge. Why is this equation true and how we prove it?
11k views

### Relation between Terminal Voltage and EMF of a cell while the cell is being charged

I know the relation between the terminal voltage, V and emf of the cell, V' while charging given by V = V' + Ir where I = Current in the circuit and r = Internal Resistance of Cell Can anyone ...
65k views

### Electric potential vs potential difference

What is the difference between electric potential and potential difference? In our course book, they are given as separate topics but their definition is given the same.
1k views

### How does resistance convert voltage to current? [closed]

This is a statement that I read mainly on books about electronics. Could someone explain why after the resistance current is what makes things work and not voltage? Example from the Art of ...
79k views

### Using AC or DC to create an electromagnet

Does it matter if I use AC or DC as a source to create an electromagnet? For example, suppose I have a coil which has about 50 turns. If I use the same AC or DC voltage, which will create a stronger ...
3k views

### Reversed First Joule's Law : heating a resistor produce voltage?

I was discussing about the theory that claims that "every emitter also behaves like a receptor": Are emitters always receptors? I was brilliantly told that this theory would be false for fluorescent ...
18k views

### If the current is increased, is there more charge flowing or is it moving quicker?

Problem Current is the amount of charge that is flowing through a component per unit of time. For a given voltage, Ohm's law tells us that if we increase the resistance, then the current must ...
10k views

### When does voltage drop occur?

Why or when does it occur in a circuit? What does it imply when you speak of a voltage drop across a resistor? (Obviously, it probably means that the current's voltage before the resistor is higher ...
621 views

### What changes in the electrons before and after a voltage drop?

It is easy to visualize gravitational potential energy as a function of the position of height, and a change in this potential is manifested in a change in height. Further, by the work-energy theorem ...
3k views

### Emf of a Cell in an Open Circuit

Consider a cell having terminal voltage $V'$ and EMF, $V$ having internal resistance, $r$ and current, $I$ flows through the circuit in which an external resistance, $R$ is connected. Potential drop ...
520 views

### Why isn't there a minus sign in Ohm's law, $V = IR$?

Suppose current runs through a resistor from left to right, and we define the left-to-right direction as positive. Then from left to right, the potential decreases. So $V,$ the voltage across the ...
3k views

### Why high voltage transmission lines?

This is a question which I seem to have tackled multiple times, solved each time after reading a dodgy internet explanation, then partially forgotten about and retackled half a year later. It is time ...
7k views

### Does the 'mAh' rating of a battery have something to do with its power?

I'm curious about the 'mAh' of a battery: how can this impact the power of the battery? I've done some research on the internet, and most of the articles I found explain about the 'amount of charge ...
3k views

### What does electric potential mean in a circuit?

As we know that electric potential at a point is defined as a work done by me to carry unit charge from infinity to that point. How can I use this definition in an electric circuit that contains a ...
818 views

### Why is voltage described as potential energy per charge?

Voltage is often called an electromotive force since it causes a flow of charge. However, it is described in terms of Joules per Coulomb or Potential Energy per Charge. Question: How does the ...
108 views

### Electric power and resistance dependance

According to the equations, $$P=VI =I^2R\,\text{ and voltage } V=IR$$ it seems clear that when the resistance is lower by fixing the voltage at constant, the current is therefore, higher, generating ...
4k 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 ...
457 views

### Ohm's law deviation

In terms of superconductivities and diodes (I do not know anything else except these), Ohm's law deviate from a linear relation. I search many titles or tags for this but I did not understand properly ...
395 views

### 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 ...
409 views

### Meaning of EMF induced in a loop

Q) Consider a square loop of side 'l' made of a metallic wire moving with a velocity 'v' which is perpendicular to one of its sides. There exists a uniform magnetic field 'B' perpendicular to the loop'...
4k 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 ...
57 views

### Is potential difference or potential used in defining capacitance?

In my textbook I came across the capacitance of a certain body (i.e. a sphere, not two different spheres as in a spherical capacitor) and in it the formula, $$Q = CV$$ where $V$ is the potential of ...
978 views

### Vibrational frequency of piezoelectric material

When a piezoelectric material experience a stress it generates voltage, and also when you applied voltage the piezo-material experience a vibrational frequency. Using oscilloscope we can determine the ...
3k views

### Does the photoelectric effect obey Ohm's law?

I've been reading about the photoelectric effect for my modern physics class, and I was confused about how Ohm's law works in relation to it. Let's say we have a photoelectric apparatus that simply ...
170 views

### Loopless voltage measurement

I think we are all very well familiarized with the classical voltmeter. Classical voltmeter has two conducting wires that bring two potentials into the box. In the box we have well controlled ...
5k views

### Calculating the electric potential in cylindrical coordinates from constant E-field

I am having so much trouble with this problem. I feel like I shouldn't be, but I am. A uniform electric field, $\vec{E} = E_0\hat{x}$. What is the potential, expressed using cylindrical coordinates,...
321 views

### Are square wave harmonics real-life phenomena or just mathematical abstractions?

Based on my limited knowledge, it is my understanding that square waves can be mathematically broken down into an infinite sum of sinusoidal waves (of different amplitudes, frequency, etc) . This is ...
3k views

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

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 ...
235 views

### How dangerous is a parallel plate capacitor which is used in physics demo experiments?

How dangerous may it be when experimenting with a parallel plate capacitor typically used in physics demonstration experiments? Take for example this one (that's what I use): http://www.ld-didactic.de/...
5k views

### Basic questions about voltage drop in DC circuit

I understand all the concepts of what voltage is using all the analogies but some things related to the drop of voltage across a circuit confuses me. If I had a short circuit and attached a voltmeter ...
7k views

### Formula for Electrical Arc Length

I was playing with some High-Voltage the other day, when a question popped into my head. Can you calculate length of an electrical arc? It probably would be proportional to :- 1. Voltage of the source ...
2k views

### Calculating the Potential from the E-Field

I find that often times I'll be tripped up by questioning whether or not I can do something mathematically, and be unable to come up with a satisfying answer. This is, unfortunately, one of those ...
101 views

### Doubt about the working principle of a silicon solar cell

I'm studying crystalline solar cell and their working principle, but I still don't completely understand the process. First of all, I understand that we dope a pure crystalline silicon with boron and ...
3k views

### The Zero Electric Potential of the “Earth”

I know its the potential differences that matter and generally we define the zero of the electric potential according to our convenience. I would like you to look at this standard problem: Charge $-Q$...
377 views

### Why are high voltage lines “high voltage?”

If I have two spheres of the same size and one sphere has a small amount of charge compared to the other that has a lot more charge, then clearly the sphere with the larger charge has a larger voltage ...
627 views

### How does a battery work and create a field inside it? [duplicate]

There is an explanation of how a battery works that says that inside the battery (in the positive charge convention) there is a field and the battery does work on the positive charge against the field ...
37k views

### Confusion about P=VI and V=IR

If we look at $P=VI$, we see that if the current doubles then the potential difference is halved but this doesn't seem to make sense according to $V=IR$. If we look at that equation, since the ...
641 views

If I put a higher voltage bulb in my car headlight, what will happen? I haven't tried it yet, but I'm wondering if it would matter. The bulb has the same wattage but a different voltage.
176 views

### Definition of Voltage using integral: minus sign?

So I'm studying electrostatics and I came across to two different definitions of potential difference/voltage (because we're in stationary regimes) and I'm having trouble understanding how the ...
97 views

### Why does current remain constant in a series circuit although the rate at which they flow deceases due to the collisions they go through? [duplicate]

I am really confused and frustrated as I can't figure this out. If someone could clear my doubt, I'd be really thankful. According to my textbook current is the rate of flow of charge, it is ...
251 views

### Can a liquid insulator be electrically charged by touching a charged conductor?

Can a liquid insulator be electrically charged by touching a charged conductor? I understand that solid insulator will only be charge on the surface where it is touch, but the case is different ...
4k views

### Difference between voltage and potential energy in a capacitor

I'm confused about the difference between voltage and potential energy in a capacitor. Suppose you have a capacitor with a voltage V and capacitance C, and you release a particle with charge $+Q$ from ...
442 views

### Capacitors and Voltage

Imagine if I have a capacitor, connected to a battery of $12 V$. After charging the capacitor, I increase the plate separation. Then my capacitance decreases, right? But charge should be conserved,...
3k views

### Why does the potential drop across a battery and resistor equal the emf of the battery?

In this diagram you can see the potential difference across the battery and resistor is the same as the pd created by the battery (the battery and resistor are representing a battery with internal ...
5k views

### Power dissipated on internal resistance of short-circuited voltage source

Suppose we have a voltage source with an EMF of $\mathcal{E}$ and an internal resistance $R$. If we connect to it a perfect wire with zero resistance, we get a short circuit. The value of the current ...
63 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?