# All Questions

138,086 questions
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### Vector potential of magnetic monopole

I am following the step on this introduction to magnetic monopole. I understand that the vector potential produced by semi-infinite solenoid is exactly the vector potential of magnetic monopole. But ...
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### Velocity of an object orbiting on a string

First, I'm sorry if this question is dumb, incoherent or vague - I never really studied any physics and this might be out of my grasp, but I tried to apply some of the math I know and figure these ...
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### Feynman story: providing two different explanations for the same phenomenon

There's a story told about Feynman in a non-scientific book (whether written by him or another, I don't recall) that I'm trying to track down. If I recall correctly: he's part of a group (perhaps ...
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### Is it true that any electrostatic charge density can be represented by Dirac Delta function?Give me a general example

My college professor said that any charge density can be replaced by Dirac Delta function but how I want to know.
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### Is the total mechanical energy conserved in a system that's a simplifying approximation of an actual roller coaster?

Suppose you have a 2-dimensional Euclidean space where one dimension goes left and right and the other dimension goes up and down where one of the units of length is the meter. Furthermore, suppose ...
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### When a proton attracts an electron in the electromagnetic field is the proton “bending” the field?

As the question states when a proton attracts an electron in the electromagnetic field is the proton "bending" the electromagnetic field like the earth bends space time ("creating" gravity)?
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### How does reflection and refraction of light behave for a colloidal solution of glass nanoparticles?

If I have a colloidal solution of glass nanoparticles (10-100nm diameter), how much of an effect does refraction and total internal reflection have on the transmission of the light? I know that if the ...
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### Misconceptions in spontaneous symmetry breaking

Spontaneous symmetry breaking occurs when we have a potential like a mexican hat as shown in figure (right) and is unbroken for the potential shape as shown in left figure. Under the Symmetry ...
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### Is there an electronic version of diffuse mismatch model for metal-metal contact thermal resistance?

Interfacial heat transport in phonon systems is routinely described by diffuse mismatch model for phonons. Has anyone come across a similar model to describe interfacial heat transport in electron ...
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### Clarification on Bernoulli's Principle

I need a clarification about Bernoulli's principle. The standard way in which this principle is taught is related to a picture like this one where usually the two sections have different areas and ...
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### Work of centrifugal force cartesian coordinates

Hey I have a question about an expression in the textbook of Born. There a pendulum of variable is considered. Then it is stated that for shortening a work given by -ml \int \dot{\phi}...
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### Understanding $\alpha$-decay energy level scheme

I want to understand the $\alpha$-decay of $242$-Curium to different excited states of $238$-Plutonium (image taken from Introduction to Nuclear Physics page 258; Author: Krane): There are two main ...
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### Need help with a phase transition problem [on hold]

I need to verify these plots and also find critical indices. Please, help me.
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### Pair production problem, how is energy not conserved here?

The problem is asking me to find the minimum photon energy that would produce an electron-positron pair when it collides with a free electron at rest. This is my attempt at trying to conserve both ...
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### What is a good introductory text on statistical mechanics for math-student [duplicate]

Here a "math-student" is an advanced undergrad or a 2nd-3rd-year grad student but only has taken the first-year undergraduate physics classes. Ice-type models, Yang-Baxter Equations are of particular ...
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### Rotational contribution towards heat capacity of an ideal gas made up of arbitrary shaped particles

Consider the particles of an ideal gas to be arbitrarily shaped, but all particles have the same shape. The Hamiltonian has a translation term and a rotational term. The translation contribution ...
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### What are direct experimental evidences that quarks exist? [duplicate]

Now we have very established model of quarks explaining fundamental strong interaction. What are experimental proofs for existence of quarks and what is the name of physicist which made them?
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### How does the Torricelli barometer create a vacuum at the top of the tube?

Hi everyone! Can someone explain to me how does the Torricelli barometer creates a vacuum at the top of the tube? And how does it work?
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### Extension as independent variable?

For a force extension graph of a spring to have extension on the $x$ axis means that you change the extension of the spring, and measure the force needed to do that? Why do these exist doesn’t it ...
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### What's the spin rate of an “earth ball”, as far from the sun as it is? [on hold]

I'm a EE (Electrical Engineer), and it's a while since I've had done any mechanics from my years of schooling, also a minor in mechanical engineering, but not using it "on the job." Last night, I had ...
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### Would Color Confinement apply in higher dimensions?

As I understand it color confinement comes from the fact that as the distance between two color charges increases the color potential energy increases, instead of decreasing, and the energy needed to ...
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### Manipulating Dirac Notation

I have trouble getting my head around manipulating Dirac notation, it's still new to me and I'm not used to it. I'm following the rotating wave approximation derivation for Rabi oscillations and light ...
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### Who had proved that neutron is elementary particle? [on hold]

We have idea that neutron is similar to proton well established. But what were proofs initially, who did them and how? Update: I mean that when neutron was discovered, it became obvious that is is ...
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### Plane capacitor with two dielectrics [on hold]

A parallel-plates capacitor has plates separated by a distance 1.0 mm. The space between the plates is completely filled with two slabs made from different dielectric materials. One slab has thickness ...
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### Only getting positive values for induced voltage?

We have to draw a voltage over time graph for the induced voltage in a coil for 2 whole turns. $N = 10$ $B = 30mT$ $A = 100cm^2$ The coil is rotating at 20Hz We have the formula: $2πNBAfsin(2πfT)$ ...
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### When is a decay mediated by the weak force

If a $\pi ^+ \to \nu_\mu+\mu^+$, here quark flavour is lost entirely. I am aware the weak force mediates decays where quark flavour is not conserved. But If I consider a $p+\bar p$ annihilating, here ...
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### Science Fiction Question [on hold]

I have been reading some scifi articles where 100 kg weight is surrounded by an "antigravity" shield and accelerated to the speed of light. If the shield was suddenly removed once it was at C, what ...
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### Does the weight of a steel ball changes when submerged in water?

Will there be a difference in the weight of just the ball under water Vs in normal atmospheric pressure conditions i.e. a weighing scale with the steel ball on it Vs in vacuum assuming earth's gravity ...
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### Effect on the weight of a bird in a closed cage with a spring attached to it

I have read the question which where the difference in the weight of the bird in a closed and a open system is described. But what happens if there is closed cage but there is also a spring attached ...
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### Operational amplifier characteristics [on hold]

What are the differences between the Open and Closed loop gain of an operational amplifier? Also, what is the concept of “feedback resistance” in amplifiers?
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### Relation of Corresponding principle and law of large numbers

Is it possible that Corresponding principle can be derived from the law of large numbers? Also is the principle a postulate of Quantum Mechanics?
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### Capacitance of Three Metalic Cylinders [on hold]

Three concentric, thin, long conducting cylindrical shells have radii of 12, 47, and 137 [cm]. The space between the shells is filled with air. The innermost and outermost cylinders are connected at ...
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### What is the energy source for Earth movements?

What is the source of energy responsible for Earth movements (rotation, translation, etc.)?
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### Effect of the magnetic field of a moving charge on the magnetic field used to accelerate the charge

Ok, so my brief understanding is that an accelerating charge will produce a magnetic field. If the charged particle, say an electron is being accelerated by a magnetic field, how does the electron’s ...