All Questions

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How does one decide if the process if beta decay positive or beta decay negative?

I've been given a sample and a daughter product and I'll have to write down the other products of this decay process. This is a beta decay due to the mass number A being constant in the sample and the ...
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When one blows up a latex balloon, why does it get easier to blow once it has a little air in it (after 1 or 2 breaths)?

When one blows up a latex balloon, why does it get easier to blow once it has a little air in it (after 1 or 2 breaths)?
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Making a Bound State with Gamma Rays (and other Very High Energy Particles)

One obvious consequence of any finite potential is that a high enough energy wave-function will not form a bound state, either they are high enough energy they will generally just bypass the barrier ...
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Very basic question. Please show where I'm wrong in the following reasoning. The movement of an object in function of time could be described as $$x(t) = v t + x_{i}$$ if velocity is constant. If ...
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What physical parameters are really being described when a rope manufacturer cites “elongation %”?

I have a precision pulley system sensitive to micron displacements. I am having issues because I need a cord with low tensioning force, but also low stretch. I am getting some weird hysteresis in the ...
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At what distance does a negatively charged atom not influence a moving free electron?

Don't know if it would be Gauss's law or Coulomb's law or both that would come into play here... but imagine a single negatively charged, stationary atom and a single free electron passing by it a ...
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Why does a panel of glass appear translucent when viewed from the edge?

Why does this happen? From the 'front' of the panel, the glass appears transparent. But viewed from the 'edges', it appears translucent...
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what is the gravitational power of a supermassive black hole at the event horizon [on hold]

what is the gravitational power of a supermassive black hole at the event horizon i am currently theorizing time travel an would like to consider the possibility of charging a supermassive black hole ...
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Expectation value problems for non-eigenfunctions

This concerns problem 4 in this pdf file. The problems are fairly straight-forward if an assumption is made that $\psi(x)$ is an eigenfunction for the momentum operator. My question is: do we ...
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Other frequencies and breaking glass

I know an individual can use the natural frequency of glass to break it, but is it possible to break glass with a frequency other than the natural frequency? Will the glass still vibrate if the ...
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What are diamagnets and paramagnets?

A paragraph in my text reads: An atom or ion with all electrons paired is not attracted by strong magnets and is termed 'diamagnetic'. In contrast, spins do not cancel when unpaired electrons are ...
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Theory of chaotic systems : Bijective mapping

Considering a one-dimensional chaotic map $T$. The domain of the map (the closed interval $[0,\,1]=I_1 \cup I_1$) is partitioned into two regions (i.e. $I_0\cap I_1=\emptyset$): $[0,\,A] = I_0$ and ...
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What is the meaning of dielectric constant with AC fields?

I understand that in the DC case for parallel plates, a dielectric constant tells you by what factor the electric field gets reduced in the dielectric material vs. in vacuum. Does the same ...
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Wire loop in the magnetic field

I have strange problem, and no idea how to solve it. The wire loop $ABCD$ is in a magnetic field of the long thin rod magnet with a magnetic moment per unit volume of $\mathfrak{M} _0$ and a ...
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Torque required by motor to overcome magnetic force and gravity

I are trying to determine the torque and Power require from 2 nos motors to drive a wheeled robotic machine aka Crawler to overcome its own weight (Gravity) and force of the magnetic attraction. ...
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how to build an anti proximity alarm [migrated]

I am trying to build an alarm that works in an opposite way to a security alarm in a shop. In shops RF tags on items set off an alarm as you walk through a detector. I wanted to build alarm that ...
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The image current due to moving charges and a current carrying thin wire

Suppose we have a plane conductor and positive charged particles of mass m are moving parallel to the plane conductor at a distance d. The trajectory can be assumed to be straight. An image current ...
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Why Quantum Information was defined? [on hold]

Quantum Information Theory is a very much discussed term in Theoretical Physics, Information Science and Mathematics. Till now nearly 50 years after first definitions we have no usage in Computer ...
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Is SHANNONs Information Theory useful today? [on hold]

SHANNON by himself excluded "psychological considerations". He was criticised very soon, because the word Information was used since time of Romans (informatio).
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Explain why quantum behavior is not observed in daily life

People always ask: How come we don't see any "Wave" attached to a classical object such as a car? You always see the object in the same place without any uncertainty. I am sure there are answers, ...
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Photoelectric effect and light coming in chunks

I was watching a lecture on introduction to quantum mechanics.While explaining the photoelectric effect,the lecturer mentioned that we must think of light as coming in chunks with each chunk having ...
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Difference between thin film interference and Bragg diffraction of electron

Thin film interference is given by: $2dsin\theta=n\frac{\lambda}{n_i}$, where $d$ is the thickness of film, $\theta$ is the angle between incident light and tangent to the surface, $n$ is an integer, ...
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Post mortem measurement of particle-wave duality

I was wondering what the outcome of this experiment would be: You shoot single photons at a double slit. On their way there you preform a measurement in $x$ so you get the time ($t_0$) the particle ...
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From a simple point of view in GR/QM we take a virtual pair creation and presumable they reunite shortly in flat space-time probably representable by a space-time warpage that generates geodesic ...
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Basic concepts on Electricity [on hold]

How do electrons move? I mean really do they move? I read that they move in circular shells AROUND THE NUCLEUS. How can they move in the conductor? I have read that there are valent electrons that ...
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Mach-Zehnder interferometry wave functions

Consider the set up below: I have read that in the apparatus the wavefunction is given by: $$|\psi \rangle=e^{i\theta}|c \rangle +i |b \rangle$$ where $\theta$ is the phase added by the phase ...
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What force needs to be applied to produce twice as much acceleration as already present in a body?

Let the current body of mass $m$ be moving with acceleration $a$, produced by applying $F = ma$. So, I thought that if I apply force $F$ again (same magnitude and direction as before), I would get ...
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Is there any other momentum besides the Poynting momentum stored in an electromagnetic field?

I am having some conceptual difficulties with energy and momentum stored in the EM field. The force density at a point is $\rho E + j\times B$ Because of conservation of momentum, and because the ...
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Incoherent Intermediate Scattering Function from Molecular Dynamics Simulations

I want to calculate the incoherent intermediate scattering function (ISF) using the self-part of the van Hove function. When I plot the ISF as a function of time, should I consider the modulus of the ...
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Electrostatics Problem - A non-conducting cylinder [on hold]

A nonconducting cylinder of radius 1.20 meters and length 2.00 meters carries a charge of 50 micro-coulombs uniformly distributed throughout the cylinder.Find the electric field on the cylinder axis ...
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How to go from Lorentz gauge to Coulomb gauge?

I want to know that if I find some solution, say a polarization vector in Lorenz gauge. Now I want to go to Coulomb gauge. There must be a transformation that links both the gauges. How would I find ...
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Motion in oscillating field: expanding in powers of $\xi$

I'm reading an excerpt from Landau/Lifschitz's Mechanics book about motion in oscillating fields. Two equations for the motion of a particle with mass $m$ are set out: m\ddot{x} = ...
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What is the significance of Planck charge?

It seems for me that Planck units are somehow connected to limits where our current knowledge breaks down because of (quantum) gravitational effects. Please correct me if I'm wrong. For example ...
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Why does the temperature of a gas inside a moving container not increase with velocity?

A rectangular (simplified) container with rigid surfaces, has a certain mass of ideal gas within it, and it accelerates in free space, undergoing rectilinear motion. There are no dissipative ...
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Addition of states of two different Hilbert spaces

I am having difficulty in understanding the following. Let us say, I have two mutually exclusive Hilbert spaces $H_1$ and $H_2$. Let these have the basis states $\lbrace|\psi_1\rangle\rbrace$ and ...
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Bifurcate Killing Horizon of the Ads-Schwarzschild solution

I need your help. I'm considering the AdS-Schwarzschild solution: $ds^2=V(r)dt^2 + \frac{1}{V(r)}dr^2+r^2dΩ^2$ where $V(r)=1-\frac{2m}{r}+\frac{r^2}{l^2}$ with $m$ the mass of the black hole and $l$ ...
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Magnetization of a type I superconductor

How could I derive an expression for the magnetization of a spherical type I superconductor? I've searched in many sites but I haven't found any way to proceed.
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What about a surface determines its color?

Light falls on a surface. Some wavelengths get absorbed. The other are reflected. The reflected ones are the colors that we perceive to be of the surface. What is the property that determines, what ...
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Is Arc reactor really possible?? and do the findings fit onto it? [on hold]

Since this is a fictitious device, and it has no "official" scientific explanation in the Iron Man canon that I'm aware of, I'm going to make something up. I'm mixing real science and fake science ...
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Can water seep in?

Today morning I was sweating a lot, and a drop of it directly fell on my iPhone's home button. Considering the height of fall to be approx. $30 cm$, I started wondering whether water could seep in. ...
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Using the spin lowering and spin raising operator on a two-particle wave function, how do I do it?

You have two spin 1/2 particles in the ground state of the harmonic oscillator potential, they do not interact with each other, and the Sz projection was measured to be zero. I am supposed to use the ...
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How 'rare' is no-slipping?

I have come across a lot of questions that say something like: A ball rolls down a hill without slipping... But I have done the maths and found that a ball would only 'not slip' if the friction ...
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We know that weight is measured in Newtons. Since, $weight= mass\times gravity$. What will be the units of Newton? Will that be $N = kg\times g$ ? But we always measure our weight using the unit $kg$! ...
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Angular momentum and the Units

I'm just curious about why many physical identities build relationship with the same units as angular momentum like the action, Lagrangian$\cdot$time, Hamiltonian$\cdot$time, phase space area etc?
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Why is the electric field highest in regions of highest resistance?

I know Kirchhoff's law and that current must be constant. But what exactly is the phenomenon, from first principles, that causes the electric field to be stronger in a region with lower carrier ...
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Is a zero-energy universe necessarily also a zero-information universe?

The universe needs to be near zero energy to not crumple in on itself. Under the same logic, does it also need to have near zero information content to prevent the passage of time from burning it to ...
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Please explain the integration [on hold]

the integration of (6 - 0.06s) should be (6s - 0.03s^2). Why is the solution (12s - 0.06s^2)? It seems its factored by 2 but I don't know the explanation to it. Cheers
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simple question on torques on an ellipsoid

I have an ellipsoid, and in the reference frame where the x-, y- and z-axis are aligned with its eigenvectors I compute the torque $\vec\tau$ acting on it. And I'm asking myself how can I quantify ...
Special OPE in $\beta\gamma$ system
I would like to find the OPE $\beta(z)\gamma(w)^{-1}$ given $\beta(z)\gamma(w)\sim\frac{1}{z-w}$ from the $\beta\gamma$-system in CFT. Is it possible?