# Questions tagged [voltage]

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

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### Why voltage across the parallel capacitor or resistor remain same? [closed]

I can't intuitive understand why voltage across then remain same. I know that if that doesn't happen it will violate Kirchoff's law and it will violate energy conversation. can someone explain it to ...
463 views

### Electric power transfer

I'm reading electric power from the book "Fundamentals of physics textbook by Robert Resnick" and I have a question about the interpretation of the text. First it says "The principle of ...
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### Is it possible to charge a zero potential ball?

I've been studying electrostatic potential and capacitance and am curious about the Earth's role in absorbing charge. The Earth is often considered an almost neutral body that can absorb an unlimited ...
30 views

### How does adding a wire across a cell and a resistor change the p.d. across a different resistor in a multi-cell circuit?

I'm a A-level physics student. I'm trying to work out why closing the switch in the circuit below makes a difference to the voltage across one of the resistors. When the switch is open, using the ...
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### Earthing and Earth's voltage

I'm looking into earthing within my topic of electric fields and i'm really getting confused with the aspect of earth having zero potential difference. My understanding of potential difference is that ...
102 views

### Do step-up and step-down converters violate Ohm's law?

I am talking specifically about DC step-up and step-down converters. If I have a certain circuit with a converter that would change the current and the voltage 2x, would not that mean that the ...
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### Can you loop a charge pump?

Is it possible, to charge two capacitors in parallel(eg. each two volts). Discharge them in series to a third capacitor(4 volts). Charge the first capacitor again with the initial voltage(2 volts). ...
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1 vote
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### A capacitor partially filled with dielectric [closed]

Assume a parallel plate capacitor that was charged up to $Q_0$ from a source $U_0$ and then disconnected from the voltage source. The plates have an area $A$ and the distance between the plates is $d$....
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1 vote
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### Electrostatic potential outside of a charged ball [closed]

To preface, I have never solved Maxwell's equation or his resulting Poisson's equation in any coordinate scheme, nor am I a physics major. I'm entirely teaching myself how to do this, so I don't know ...
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### Does the geometric shape of the cross-section of an infinitesimally thin conducting charged thread (wire) affect its electric field?

Assume that a solid conducting torus (toroidal ring), with a cross-section of a circle of (minor) radius $r$, is negatively charged. Solving Poisson's equation, we can find the charge distribution of ...
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### Why do lamps in circuit have potential difference but two points in cable without anything in the middle of it have no potential difference?

I'm preparing for my EE major, this is my starting point.
1 vote
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### Visualization of resistance [closed]

What does a resistor do in an electrical circuit? Does it impede the flow of electrons by increasing offering a path that offers a large no. of collisions? How can i visualise it, i have been told to ...
70 views

### Voltage: work to move a charge, or difference of electric potential?

Let's say I have a single positive charge inside of an electrostatic field. I want to move this charge from point A to point B and determine the voltage between the two points. Points A and B are the ...
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### Why is my idea of voltage drop wrong?

when battery is connected to 2 ends of a wire, potential difference is created, this causes electric field causing electrons to move, the field gives the electron electric potential and the thus ...
105 views

### Understand power rating in layman terms

I have recently started the chapter of electricity of class 8. I am not understanding the concept of power rating of appliances. When we say that a bulb is rated 220V-100W, which means, according to ...
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### Maxwell stress tensor on a capacitor late given a dielectric

Given a capacitor with large plates (area $A$) separated by a dielectric with relative permittivity $\varepsilon_r$ and thickness $g$, I believe the Maxwell stress tensor states that the force on each ...
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### Equivalent capacitance for a system of spherical capacitors

The question demands equivalent capacitance of two concentric metallic shells with larger and smaller radii. b and a respectively. The inner sphere is just left open(it's not earthed or anything), and ...
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### How do I compute the voltage accross a cell membrane given microstate of neuron (distribution of charged ions)?

I am not a physicist, and I'm not sure what keywords to use to search for this. I'm trying to understand how I could in theory quantitatively know, what the voltage across a cell membrane in a Neuron ...
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### Potential difference when two emf sources are connected in a simple loop circuit

I am having difficulty understanding the equation below for the potential difference between the two terminals of an electromotive source when two sources are connected from Sear and Zemansky's ...
1 vote
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### Ozoneless air ionisation

Is there some way to ionise air in way that removes or atleast decreases ozone production? Is some combination of electrode shape, electrode material, negative or positive voltage, dc or ac and ...
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### Can a positive charge have a negative potential?

I'm studying about electrostatic potential due to a point charge and was wondering - can a positively charged point have negative electrostatic potential? V=Kq/r for a positive point charge. Assume B ...
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1 vote
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### Does it make a difference whether potential difference is denoted as a negative or positive value in an answer, since it's just a scalar? [duplicate]

Does it make a difference whether potential difference is denoted as a negative or positive value in an answer, since it's just a scalar? Sorry if it's a dumb question, I was just a little unsure.
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### Is there any electronic devices that maintain charged state?

I want to know how to make electronic devices that are continuously charged to + or - state on which surface when voltage is applied to utilize the dielectric polarization property, or if there are ...
55 views

### Confusion about reference point for potential difference

My confusion comes from trying to find the potential difference of a spherical conductor with an inner shell of radius $R_1$ and an outer radius $R_2$. I tried using a reference point of $R_1$ and ...
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I am very new to electronics and am a physics student working on an assignment. I have a very simple circuit set up in my bedroom: A power source of DC +0.7A and +5.0V with a single resistor of 100 ...
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### Behaviour of current in Pure capacitive circuit with DC voltage across

A circuit has just 1 capacitor and a DC Battery (V volts) and the wire has no resistance. At time $t=0$ the capacitor is completely uncharged. How current in this circuit changes with time? What i ...
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1 vote
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### Electric Potential in circuit confusion

I reviewed some of the fundamental physics and I looked back at the equation for Electric potential at a point p: $$V(p) = k \sum_{i} {\frac {q_i} {r_i}}$$ where p is the point at which the potential ...
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1 vote
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### Why does current lag behind voltage by 90° in an inductive circuit?

We can easily prove this with KVL, a little bit calculus, and trigonometry. We get voltage as a sine function and current as a cosine function. Then we apply 'Add sugar to coffee' and get that current ...
50 views

### Equipotential surfaces

Why two equipotential surfaces cannot intersect What is the logic and reason behind it?I know that two electric field lines cannot intersect but what about equipotential surfaces?
1 vote
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### Electrostatics: Electric Potential of Earth [duplicate]

I have a very basic question which is: Why we consider the potential of Earth to be zero? Generally in physics we consider the electric potential at infinity to be zero. But while reading about ...
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### What does this formula of Electric potential generated by spherical symmetric charge density mean?

I found this formula (14.5) in the book Classical Electromagnetism in a Nutshell by Anupam Garg, $$\phi(r) = \frac{1}{r} \int_0^r 4\pi r^2\rho(r)\;dr+\int_r^{\infty}4 \pi r\rho(r)\;dr.$$ I know it's ...
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### Equation of a equipotential surface

I have been trying to find a equation for the equipotential surface of a dipole , so I started with a simpler system of a singular charged particle , here are few things I know about the equipotential ...
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### How is power dissipated proportion to current and current squared?

$P=IV$ and $P=I^2R$. Does this mean that $P$ is proportional to both $I$ and $I^2$? I don't understand this concept. And when should I use the various formulas for power? When another variable is ...
180 views

### Why does the capacitance of a capacitor depend on charge and potential?

The formula of capacitance is $$C = \frac{Q}{V}.$$ So the capacitance of a capacitor should depend on the charge and potential but it doesn't. Why?
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### What is the voltmeter measuring the PD of?

In the circuit diagram, the cell has an internal resistance, but when the switch is closed what does the voltmeter measure, the pd of the cell, or the components in series?
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### How could free electrons flow in a conductor? If electrons actually flow in a conductor, then won't the atoms of the conductor become unstable?

I've read in many physics books that electrons flow due to a potential difference across a conductor, and that the flow of electrons is opposite to the current direction. But, if electrons move from ...
809 views

### Could there be no current through a wire with a difference in voltage?

So I made this circuit on a simulator to help with my physics problem at school. As you can see from the picture, there is a voltage difference of 5V between B and D. I know that the voltage ...
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### I'm trying to figure out how to go from the electric potential of a uniformly charged semi-circle, to the electric field

The question asks "A thin plastic semi ring of radius $R$ has a uniform linear positive charge density $\lambda$. a) Determine the electric potential $V$ at point O, the center of the semi ring. ...
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### Can the potential of a point charge be considered one-dimensional?

It is well known that,take infinity as 0 potential,the potential at position r of a point charge q placed at the origin is $$V = \frac{1}{4\pi \epsilon _0}\frac{q}{r}$$ it satisfies three dimensional ...
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