All Questions

In spherical coordinates $(r,\theta,\phi)$, the stationnary diffusion equation is a Laplace equation $\Delta f =0$. The solution in a radial symmetry : $f=f_{\infty}-r_0/r$ where $f_{\infty}$ and $r_0$...

Telescope here refers to a system of two convex lenses. In one of the problems I wanted to solve, it is given that "a Barlow lens of focal length $f_{b}$ is placed at a distance $D < f_{b}$, from ...

The following quiver plot shows principal direction and magnitude of a vector field in every point of a 2d grid. I'd like to condense the representation to nodes and graph edges -- unoriented edges ...

I am trying to solve a Physics question which includes air density of Mars and with my calculation, I'm finding value around 0.01045: ρ_(mars,air)= P/RT= 600/((287.05).(200))=0.01045. But my ...

No matter how much I think about this I can't come up with a reason to me there is no difference In the forces acting against the tilting of the bike in both the cases as mothion is in the ...

When the Ising model Hamiltonian $$H=-J\sum _{<ij>} \sigma _i\sigma _j-H\sum _i \sigma _i$$ is assumed ($\sum _{<ij>}$ is the summation over all the bonds or adjacent pairs of sites, $\...

I am doing a 2D MD simulations of charge carriers in graphene using the Leapfrog algorithm. I am trying to prove that, in some specific cases (when distance between particles is small), the method is ...

The background: I am looking at Compton scattering in its most general form with $p+\gamma^*\rightarrow p'+\gamma'^*$ in the Breit-frame (which implies that in my case $\vec{p} = -\vec{p}'$). The ...

Let's have an ideal conductor with current density $\mathbf{J}$. The ideal conductor takes up the entire space, effectively resulting in the entire space $\mathbb{R}^3$ being permeated with $\mathbf J$...

What happens when an electric dipole is kept in a nonuniform electric field?

I have polymer statistics homework that i need help on: 1) Determine the force-extension behavior of the freely jointed chain (FJC) and the worm-like chain (WLC) models of polymers in the limit of ...

I want to prove that if $ \langle \psi | A | \psi \rangle = 1$ for all $ \psi ,$ then $A=I .$ Let's write $A$ and $\psi$ in the same basis. $$ \begin{alignat}{7} \left\langle \psi \middle| A \...

As it is claimed in this question, the identity operator is an hermitian operator, but not an observable. However, if I were to build a device, which only measures the existence of an electron in a ...

Which piezoelectric coefficients are suitable for which application? For example, we know that high piezoelectric charge constant are used in generators and actuators.

Why doesn't it release all the photons in one shot? I am referring to both in the cathode ray tube and also in the vacuum of space.

Because Coulomb's constant only has 1 sig fig, should all of my answers have 1 sig fig when doing a problem with Coulomb's Law?

In Morin’s Mechanics book, a problem called leaky bucket goes: 5.17. Leaky bucket ** At $t = 0$, a massless bucket contains a mass $M$ of sand. It is connected to a wall by a massless spring with ...

Imagine 2 neutrons placed at some distance apart, they should only gravitationally attract each other according to Newton law of gravity. Theoretically the law should work at smaller distance until ...

This occurred to me when I was reviewing the Laughlin argument. Suppose a gauge transformation $A\rightarrow A+\nabla{\theta}$, where $\theta$ is the angle defined in a closed loop. When integrating ...

What happens if you remove the polarization filter from a computer monitor? shows how to make an "unseeable" monitor from a LCD monitor, i.e. one that requires special glasses to view. I was wondering ...

in science class, we have to do slides on the different aspects of waves. I was wondering if anyone could explain to me how to find the energy of amplitude

I think I am completely misunderstanding a concept here. Depending on my approach, I get two different answers, which I shouldnt (as I understand)/ The Setup: A ...

A large spool of rope rolls on the ground with the end of the rope lying on the top edge of the spool. A person grabs the end of the rope and walks a distance, holding onto it, Fig. 8–64. The spool ...

Does frequency depend on the number of wavelength the source makes per second? Is it wavelengths? And what is the definition of amplitude?

How would you prove the moment of inertia of a cone rotating around from its peak about the y-axis? I've added a roughly drawn picture for better understanding.

I have a deep water well, with a length of 1/4" drip tubing, open at the bottom, taped to the pump 180' down. The other end of the tubing is connected to a gauge pressure sensor in the cabinet of my ...

Why do light and sound waves under change in phase on reflection and is the change in phase for displacement and pressure wave the same in case of sound waves??

I imagine they would need keep a certain distance away from each other.

Does the same force that holds the electron in orbit around the proton hold the Earth in orbit around the sun.

I'm solving a dynamical system of a ball of mass $m$ and radius $R$ rolling on a rotating platform ("turntable") for which I found the Lagrangian to be: $$L=\frac{1}{2} m (\dot{x} - \Omega y)^2 + \...

I am trying to understand a calculation which has to do with Bell's Inequality. They start with an entangled state of an elecron and a positron which are measured along an axis a with + meaning up ...

I'm just wondering about the transition state of a transitional metal before (ex: [Ar] 3d3 4s2) and after ionisation (which means [Ar] 3d3 4s1) because before ionisation the 4s level is closer to the ...

I'm confused about where we should put tensor indices when we vary an action wrt the metric. For example, if I have in the Lagrangian a term such as $$ A_{\mu\nu}B^{\mu\nu}, $$ do I necessarily have ...

Just look at the L.H.S of the compressible navier-stokes equation from wiki $$\rho(\partial_t \vec{u}+\vec{u}\cdot\nabla\vec{u})=...$$ How can I add a vector $\partial_t \vec{u}$ and a scalar $\vec{...

This question is inspired by the following example given in Barnett's book on quantum information: (PDF here, starting at the bottom of page 5) I am not a physicist, but I'll accept that the ...

An ideal gas of non-relativistic particles is in a box with perodic boundary conditions. I've shown that its chemical potential is given by: $$\mu=-kT\ln \left( \left( \frac{2\pi m}{h^2} \right)^{3/...

If the photon in electromagnetic radiation does not have mass then does this mean that electromagnetic radiation is not subject to gravitational forces. Therefore it would continue at the speed of ...

Take a black hole singularity of sufficient size that a planet could be placed in a stable orbit with a high amount of time dilation observed from the outside. Let’s assume it’s a pretty big black ...

I'm trying to find the Lie derivative of a 2 form $\sin(\theta)d\theta d\phi$ with respect to a vector field given in a differential basis and I think the way to go here is to use Cartan's formula but ...

Consider an electric dipole consisting of charges $q$ and $-q$, both of mass $m$, separated by a distance $d$. If the dipole is given an acceleration $a$ perpendicular to its moment the total ...

According to (super)string theory, each fundamental particle represents a different vibrational mode of a relativistic string and each type of vibration pattern represents a different particle. But ...

We are told by our chemistry teacher that all chemical reactions take place as reactants (that have bigger potential) change into products (that have smaller potential) hence instable substances ...

What mean: "An electric field (which is static) is not a source of energy (which comes from the electron), it is a 'store' of potential energy."

Reading some introductory texts to general theory of relativity (GR), I understand that the gravitational force between two objects has, in addition to the component in the direction of the vector ...

Is it possible to discharge for example an OPC drum without exposing the surface? Since they are usually build on aluminum tubes (and belt type OPCs on metallized PET or other polymer) could one drop ...

The super-Poincare algebra contains supersymmetry generators $Q^I$ which satisfy fermionic anticommutation relations. By the higher-dimensional analogue of the spin-statistics theorem, they must ...

In $d = 3+1$ dimensions, the spin-statistics theorem states that fermionic particles have half-integer spin and bosonic particles have integer spin, in a well-behaved relativistic quantum field theory....

I found this question here but it does not fully answer my question. The answer there was that "composite bosons can occupy the same state when the state is spatially delocalized on a scale larger ...

There are 2 charges q1 and q2. The distance between them is divided into 2 parts: one has a medium with dielectric constant K1 and the other has a medium with dielectric constant K2. The length of the ...

I am studying loop quantum gravity using the book by Pullin and Gambini. I am having some trouble understanding and getting past the chapter on Yang Mills theory, mainly because I am confused about ...