Questions tagged [voltage]

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

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72 views

What exactly does Ohm's law say?

Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance, R ...
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Relation between electric potential and Electric field

I'm unable to understand why the integration of $\mathbf E$ is done in two different ways for constant $\mathbf E$ and varying $\mathbf E$, as in case of parallel plate capacitor and spherical ...
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Ambiguity between electric potential and voltage?

I understand that electric potential is a location based measure of electric potential energy per unit charge in an electric field, and that voltage is then the difference between two electric ...
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45 views

Is the current on one side of the bulb more than the current on the other side of it?

Go easy on me if you find this question stupid, just another high schooler here. So here's what I am thinking.A battery "pushes" electrons through a circuit due to the electric potential difference ...
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Electric field inside a homogenous distribution for slightly different Coulomb's law

I am trying to show that the electric field inside a homogeneous distribution of superficial charge is of the order of magnitude of $\delta$, with: $$V(\textbf{r})=\int d^3\textbf{r'}\frac{\rho(\...
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76 views

Why connect plug wires in a certain way when polarity changes in AC anyway? [duplicate]

In AC systems the two wires of a circuit alternate polarity many times per second. So positive and negative switch, half of the time a wire is positive the other it is negative. So why is it ...
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Current in RC circuit

Why is current drawn in an RC circuit (in a circuit powered by DC voltage supply) independent of the capacitor used? While the capacitor is charging current drawn from the battery only depends on ...
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2answers
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Components of Electrostatic energy to components of electric field?

I'm trying to understand the relationship between electrostatic energy and the electric field so that I can compute electric field components from electrostatic energy components. Is it correct to ...
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38 views

What is causing the current sinusoidal delay regarding voltage in inductive circuits? [duplicate]

Do electrons acquire some electromagnetic 'mass'as they have so much slow acceleration in the coil due to obviousely electromagnetic field acting on them or it is just the net voltage that drops down ...
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Basic question on Ohm's law

I have what I assume is a very basic question on Ohm's law. Let's say that we have $n$ equal light bulbs in a series with a battery. We know that $$ U - IR - IR - \cdots -IR= U - nIR = 0.$$ Solving ...
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Significance of the negative sign in $V=-\int \vec E · \mathrm d\vec r$ [duplicate]

Why is there a negative sign in the relation $$V=-\int \vec E · \mathrm d\vec r$$ between the electric field and the electric potential? Is this because of some derivation in vector calculus because ...
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364 views

What happens when electrons reach the battery?

We have a capacitor which is connected to a voltage source. The top plate of the capacitor is connected to the positive terminal of the source. Therefore, electrons go from the top plate to the ...
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Why does inductor current lag the applied voltage at its terminal by 90 degrees?

I studied electromagnetism and I am currently working with Inductors. I could not figure out the physical reason based on electromagnetics on why inductor current lags the applied voltage by 90 ...
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Voltage propagation along a wire [closed]

Let's say you have a wire connected to a device that you can switch between high-voltage and ground voltage. The wire is not connected to anything on the other end. You're observing the voltage in two ...
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Open circuit voltage of solar panel in relation to temperature

How do we calculate the effect of temperature on the open circuit voltage of a solar panel? The source: https://www.pveducation.org/pvcdrom/solar-cell-operation/effect-of-temperature offers an answer,...
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4answers
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What is the intuitive explanation for high voltage and low current?

By the formula $$P=VI$$ we can say that the voltage can be increased and the current decreased by keeping the power constant. It is mathematically and experimentally right. But is there a way to ...
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What does Ohm's law mean in this context?

In this problem Griffiths states that the potential at radius $a$ and angle $\phi$ is $V(a,\phi) = \frac {V_0 \phi}{2 \pi}$ And yes that satisfies the boundary conditions, that at $ \phi = \pi$ , $ V=...
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How do you calculate a half cell potential Copper(II) and Copper Sulfate?

I have to complete an experiment for school where I have copper and zinc electrodes placed into an electrolyte of copper sulfate and I have measured the potential across it at varying temperatures. ...
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Circuit - solve Kirchhoff's laws with determinant?

Here is an exercise from my textbook. ]1 At first I solve it by using Kirchhoff's laws directly and using complex impendance: $$U_{in}=\frac{1}{Cs}(i_1-i_2)+i_1R_1$$ $$0=R_2i_2+\frac{1}{Cs}i_2+\frac{...
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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 ...
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Conservation & Flow of Energy in Circuits

Before I ask my question, it's important that you know how I understand the underlying physics of circuits, so you could point out any misunderstandings or incomplete thoughts. A battery creates an ...
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2answers
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Applying Kirchhoff Rule to an LC circuit

In a simple LC circuit (just one capacitor and one inductor), using the Kirchhoff rule has $$\frac{Q}{C} + L\frac{dI}{dt} = 0.$$ But isn't the voltage drop across an inductor $-L\frac{dI}{dt}$? What ...
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Electric Field vs Distance (Contradiction)

There was a text book question in my physics class this morning on what happens to the strength of an electric field $E$, if its distance between two plates decreases by 2 fold. My initial thought ...
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Potentiometer's working

I know that in a closed circuit with multiple batteries, current is provided by the battery which has the maximum voltage. Let's suppose that $E \gt V$. Now, the voltage $V_b$ at point $b$ will ...
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Common potential in Capacitors

If two isolated charged capacitors (of different capacitance) are connected in parallel to each other they acquire a common potential. But suppose if i connect positive plate of one capacitor to ...
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2answers
54 views

Soft X-rays and Hard X-rays

How to know how much of kilovolts are in soft X-rays, and in hard X-rays? (Ex: 80kV is in soft X-rays or hard X-rays?
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How can the electric potential be zero at a point where the electric field isn't, if that field can give a test charge kinetic energy?

Say we have 2 charges set up like above. Why is $V_3=0$ ? I can understand mathematically that the scalars fields cancel out, but I don't understand it physically. If I place a positive charge in ...
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Are my voltmeter readings expected for a correct chua's circuit?

I am following this article Robust OP Amp Realization of Chua's Circuit by Kennedy to implement a Chua's circuit. I use exactly the same design as the article; the only difference is that I use a 15mH ...
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Difference between Capacitor and a battery [duplicate]

Capacitor stores electric charge and battery also stores electric charge. SO whats the difference between them?
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85 views

Why voltage is same across parallel resistance?

Since voltage stands for energy per unit charge to be used to carry it from one point to another,why should energy per unit charge be same for two resistors of different resistances,?the energy ...
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3answers
76 views

Electric potential and drift speed of electrons through circuit

What I have since learned: (Tell me If I am wrong) In circuits ,Batteries provide electric potential difference (voltage) ,This difference creates electric field (Over the conductor or the wire) ...
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1answer
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Potential - When and when not to use infinity as a reference point?

I'm reading Griffiths' Electrodynamics and having a bit of a problem to understand when we can use infinity as a reference point and when it cannot be used. One question asked to calculate the ...
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In a circuit having one resistor why do the electrons lose all their potential energy across that resistor and not do so if there are many resistors

In a simple circuit which consists of a battery and one resistor, why do electrons lose all their potential energy across this one resistor regardless of the magnitude of the voltage or the resistance?...
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What is the fundamental reason behind electric potential decreasing in the direction of increasing electric field? Is there any exception to this?

Does this increase and decrease necessarily have to be linear in nature? I have seen this statement being thrown around which states that in direction of increasing electric field the potential ...
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51 views

How does the battery do work on the electron although the speed of electrons is constant

In a simple circuit how does the battery do work on the electrons of the wire although their speed is constant . Imagine I want to take a body which has 5 Newtons weight from the ground to 10 meters ...
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1answer
75 views

How is the rate of current change in an inductor present in a circuit maintained / decreased?

Considering an ideal circuit of DC voltage source and an inductor connected together with a switch in between them. When the switch is closed at t=0 the current starts increasing which causes induced ...
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4answers
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How do resistors generate different heat if we make the current fixed and changed the voltage and resistance? Notice the flow of charge is constant

Consider having a circuit which consists of a battery and one resistor. $V = 10$ volts, $R = 5$ ohms, so $I = 2$ Amperes, and $P = 20$ watts. If we double the voltage and resistance, the current ...
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anodized insulation and its use as dielectric [closed]

I've done anodizing before, but I had some questions regarding the anodized insulation and its use as dielectric. For example, if I want to tolerate a 1000 volt electrical failure do I have to do ...
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1answer
64 views

Confusion on negative charges, current, and direction

My text book seems to have two contradictory statements about the same subject. Under the electrical potential and capacitance chapter, it says that negative charges move from lower to higher ...
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1answer
59 views

What is electric field vector? [closed]

What is electric field vector? How to find out the Electric Field vector at a point on a equipotential surface. Please explain by giving an example.
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315 views

Which type of conductors don't follow Ohm's law? [closed]

Which type of conductors don't follow Ohm's law? I know that semiconductors and superconductors don't follow them, but why? And what about ideal conductors. What are they? Do they follow ohm's law? ...
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Why RMS for average voltage in AC current? [duplicate]

We write rms formula as $$v_{rms}=\sqrt\frac{\int_a^b[f(x)]^2dx}{|b-a|}$$ I know if we take arithmetic mean average voltage will be 0. So we want all voltage values to be positive. Why don't we do ...
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1answer
92 views

What does direction of EMF mean?

In faraday's law it mention's direction of EMF( like in closed loopit is clockwise or anticlockwise depending on direction of motion of magnet) but defination of EMF is roughly Potential diffrence ...
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1answer
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Is Ohm's Law Valid for AC Circuits?

Specifically, let us talk about a circuit containing only an AC source and a capacitor. In this case, the current is 0 at the instant the source voltage is maximum. Same is the case when the circuit ...
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1answer
25 views

How to calculate the voltage of a DC motor?

I have a DC motor. But I don't know its voltage. If I connect with a 3.2V battery, then the motor rotates. Can I find the voltage of the motor from the rpm of the motor?
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Will high voltage but low current glow a bulb?

Suppose I increase the voltage supplied to a building from a constant power source substantially by putting a transformer. Doing this would reduce the current substantially as well. So will the ...
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1answer
40 views

Electric potential / infinity is not the 0 reference

Let's say we have a charged sphere with radius $r$. Usually, the way we define its potential is $V = kQ/r$. In this way, we have defined its potential with infinity as the zero reference point. Let's ...
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Resistors equivalent using symmetry and equipotential line

I propose the following statement: In a circuit, while determining equivalent resistance across two points, if the circuit is symmetric wrt the line joining the two points , we may fold the circuit ...
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3answers
86 views

Electric Potential in the Center of a Electric Dipole

I thought the electric potential at point B would be positive because placing a positive charge at point B would cause it to move releasing energy while doing so. The answer key states that the ...
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0answers
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Velocity Selector Question with Unknown Voltage

In a diagram, electrons are emitted from a hot coil with initial velocity 0 at plate A and then pass through a uniform field between two plates (A and B) where $V=1.00\times10^4$ volts. After, they ...