All Questions

16 views

Binding energy per nucleon dependency

For a given isotope, does the nuclear binding energy per nucleon depend on the presence of electrons? For instance, if an electron was excited by an incoming photon and jumps to a different orbital, ...
35 views

Static friction and Kinetic friction

I can't seem to find this anywhere on the internet or on stack... Sadly. Very basic question: I have a block that is on a surface. The coefficient of static friction between the two is $0.3$, ...
39 views

How is a measurement on an electron done?

There are two ways how to change a direction of a qubit - one with Larmor precession, another with a measurement. I am not sure about the measurement one. Let's say I have an electron with spin ...
85 views

If the effects of gravity cannot travel faster than the “c”, does this mean we are only gravitationally bound by masses in our observable universe?

I'm 17 and fascinated by the differences and omissions Newton made in his equations of motion. However it makes sense that gravity can't travel faster than light because of the force-carrying ...
23 views

What is the correct dual of antisymmetric tensors?

In some books I find the dual antisymmetric tensor $$\tilde{H}^{ab}=-\frac{1}{2}\epsilon^{abcd}H_{cd}$$ and other times I find it with no minus sign. How can I tell which to use? Is this like that in ...
17 views

What is the speed of the charge in this setup of spherical conductors? [on hold]

Two concentric spherical conductors respectively have radius $r_1 = 0.145\ \mathrm{m}$ and $r_2 = 0.207\ \mathrm{m}$. The inner sphere carries a charge of $-6.00 \cdot 10^{-8}\ \mathrm{C}$ . An ...
19 views

Classifying solutions of equation of state as functions of temperature

I've got an exam in 2 days and the past papers don't have solutions. I'm given this equation of state: $$p + a\frac{N}{V} = \frac{Nk_BT}{V-bN}$$ and asked to classify the solutions as functions of ...
13 views

Infinite bare quantities and dressed quantities confusion

I'm getting very confused. Taking the example of the mass of the Z-boson. Constructing the GWS model using gauge symmetry breaking one finds a lagrangian which is a function of the Z-boson mass: ...
29 views

Four dimensional Bravais lattice

I am wondering if there are any reference on four dimensional Bravais lattice and their primitive vectors, even an example will help.
27 views

Reflectivity of Metals - real and imaginary part of k-vector and complex dielectric function

De electric field component of an electromagnetic wave that is traveling in the $x$-direction is given as $$E(x,t) = E_0 e^{i(kx - \omega t)}$$ with $E_0$ the amplitude and $k$ the wave vector. From ...
23 views

Semi infinite parallel conductors [on hold]

Semi infinite parallel conductors separated by a distance of 0.5 m are at the endpoints associated with the resistance R = 4, while according to the two without friction slides bar by weight: 0.1 kg ...
33 views

What exactly is closed orbit theory and what assumptions go into it?

I am just beginning a research project on the study of closed orbits, specifically as related to hydrogen, and I wanted a little bit more information on what exactly makes something a "closed orbit". ...
33 views

The approximation of the potential field of a half wave dipole antenna

I'm currently deriving an approximation of the potential field of an dipole antenna in the far-field in two dimensions, and I have some troubles. Since using two methods give two different answers. ...
24 views

In the solar system are located planet A and B [on hold]

in The solar system are located planet A and B. A and B are their heliocentric distances distance. A is planet on the outer = 1 a: e: and bypass -Time PA = 365 days. Assuming coplanar orbits. A ...
38 views

Using metric tensor to contract

Can the metric tensor also contract the indices in the $$\epsilon^{\tau\lambda\mu\nu}~?$$ For example, if we have ...
90 views

Why isn't $\bar \psi_L \psi_R$ zero?

My book gives this Lagrangian: $$L = -|\partial \phi|^2 -V(\phi) -\bar \psi_L \not \partial \psi_L -\bar \psi_R \not \partial \psi_R -g(\phi \bar \psi_L \psi_R + \phi^* \bar \psi_R \psi_L)$$ It's ...
34 views

Influence of spacetime curvature on electromagnetic wave propagation [duplicate]

Classical physics assumes that spacetime is evenly distributed in the sense that Coulomb's Law predicts that a charged particle will create a spherically symmetric electric field around its location. ...
17 views

What reasons might one have for thinking that the brownian motion of nanoparticles might improve a nanofluid's thermal conductivity?

I've been reading some papers regarding determination of the thermal conductivity of nanofluids recently. It seems that there is a big debate over whether or not the Brownian motion of these ...
40 views

Mathematical modeling literature? [on hold]

I'm currently working through my physics bachelor's degree. As many of you know, there is an enormous amount of mathematical models included in thypical physics curriculum. I enjoy learning about ...
40 views

what is the temperature (and pressure) of the oxygen inside an oxygen bottle?

In the hospital or in a lab, one can see the huge oxygen bottles. A question is, what is the temperature of the oxygen inside the bottle? And what is the pressure inside? We know the critical ...
91 views

Do clocks measure conformal time (new argument)?

Assuming the spatially flat FRW metric for simplicity: $$ds^2=c^2dt^2-a(t)^2(dx^2+dy^2+dz^2)$$ where $t$ is cosmological time, $a(t)$ is the scaling factor and $x,y,z$ are co-moving spatial Cartesian ...
25 views

Optical path difference

Hello, i have question about calculating optical path difference. $\Delta L = (BC+CD)*n2 - BF*n1$ - why calculating path difference here we are substracting $BF$ segment?
34 views

Gauss's law and charge on surface

Consider a cone (not necessarily right cone), with a charge $q$ at its apex. Fix its base, and let the vertex be movable. Now suppose we intend to find the flux through the base. Since the flux ...
38 views

Radioactivity, alpha decay [duplicate]

In alpha decay, a $\text{He}$ nucleus is emited along with a daughter nuclide. Now suppose $\text{U}$ with atomic number 92 and atomic mass 238 emits an alpha particle and a daughter nuclide is formed ...
52 views

Why Does Moving a Cup of Coffee Up and Down whilst carrying it Make it less Likely to Spill?

Sometimes I have a Very Full Mug of Coffee and I am trying to carry it without it spilling. I noticed that if I moved the Mug up and down when carrying it, it seemed to settle the coffee and make it ...
45 views

What does “Standard Model” really refer to?

I am reading the arXiv published paper by Frank Wilczek called "Physics in 100 Years". Apparently, this paper is the printed form of a talk given at Brown University earlier this year (2015). Right ...
19 views

Is it possible that gravity is created by the empty space in all matter? [on hold]

Everything is made up of atoms, which are made up of 99% empty space. Thus, everything is made up of 99% empty space; furthermore everything has gravity. Given this, is it a plausible theory to ...
18 views

Electric Flux through metal plate by uniformly charged wire

Suppose a long uniformly charged wire is placed parallel to a thin uniform metal plate of length l and width w.Distance is r.Then how to calculate the electric flux through the plate if the charge ...
14 views

Object moving with 2 linear accelerations

Say I have an object moving with an acceleration of 5 m/s$^2$. At a certain point X, due to some forces, the acceleration of the object changes from 5 m/s$^2$ to 2 m/s$^2$. Would this change in ...
42 views

Example for System Given Hilbert Space

What are some concrete examples of physical systems such that their corresponding Hilbert space is given by $\mathbb{C}$? Also, what is the physical difference between a system whose corresponding ...
22 views

Find the equivalent capacitance

On the plane capacitor below, the surface of the boards is $A$ and the distance between the boards is $d$, the dieletrics constants are $k_1$ and $k_2$. Find the capacitance of the capacitor in ...
32 views

Ohmic Heating in Wires

please could someone tell me why Ohmic losses are always referred to as $I^2 R$ losses? Here is my problem. If the power coming from a power station is fixed then you can either deliver this power as ...
2k views

How to keep a bucket of water from freezing by only natural means?

Strange question. I am working on a fictional story where a person has to carry a bucket of water for hours during a blizzard. Is there any natural way to keep a bucket of water from turning to ice in ...
33 views

One extra conservation equation or angle relation for a relativistic collision

Edit: It seems that the derivation for the center of momentum frame was incorrect, due to the fact that the center of momentum velocity changes after the collision. This is also true for the ...
34 views

41 views

Electric field outside a sphere

The sphere $K\subseteq R^3$ with radius $R$ has a homogeneous charge density $\rho$. Find the electric field E, produced by K outside of, meaning, find the integral ...
83 views

What does this equation mean?

So I have just entered 11th grade and started limits on my own but my Physics textbook has an equation which I don't understand, I suspect it uses integration which I haven't learned yet. So can ...