0
votes
0answers
10 views

Final charges on Capacitors connected in a curcuit

Capacitor C1 is charged to a Potential Difference of 10V. It's capacitance is 2 microFarad. Capacitor C2 is charged to a Potential Difference of 15V. It's capacitance is 4 microFarad. Now the ...
1
vote
1answer
114 views
+50

How to understand singularities in physics?

The question is probably two-folded and I will try not to make it too vague, but nonetheless the question remains general. First fold: In most physical laws, that we have analytic mathematical ...
1
vote
0answers
15 views

G force of common objects hitting the floor?

At my friend`s work they have an accelerometer which measures the force with which certain objects hit the ground. He claims that from a 4-foot high height, cell phones hit a solid metal surface with ...
0
votes
0answers
16 views

An inconsistency in Hamiltonian formulation for non-local Lagrangian: what am I doing wrong?

This question is based on a previous question I asked, Q. [1] In this question, I proposed an example of a non-local Lagrangian (functional), I'm revisiting it here: $$\mathbb{L}=\frac{1}{2}\int^t_0 ...
4
votes
1answer
155 views

Poles for a particle scattered in a delta potential

I am working on problem a professor gave me to get an idea for the research he does, and have hit a point where I'm having a difficult time seeing where I need to go from where I'm at. I would also ...
24
votes
5answers
3k views

If the earth is a good conductor of electricity, why don't people get electrocuted every time they touch the earth?

Since the earth is a good conductor of electricity, is it safe to assume that any charge that flows down to the earth must be redistributed into the earth in and along all directions? Does this also ...
0
votes
0answers
36 views

What happens if the big bang occurs once again?

according to string theory every universe is a large brane and big bang is a event which takes place when two branes collide with each other. if our universe brane collides with another brane there ...
1
vote
2answers
100 views

Locally flat coordinate and Locally inertial frame

I am having some doubts on myself regarding the above concepts in General Relativity. First, I want to point out how I understand them so far. A male observer follows a timelike worldline ($\gamma$) ...
2
votes
1answer
30 views

Rindler and Minkowski space future/past infinity

In my black holes course, we are looking at the Penrose diagram for 1+1 D Minkowski space. My notes don't specifically describe $i^{\pm}$ (future/past timelike infinity) but do say all timelike curves ...
1
vote
0answers
17 views

Is it possible to directly pump a laser using sunlight?

Typically in the old days one would use a flash tube to pump a ruby crystal. Is there any way, or any lasing material, that could use concentrated sunlight directly for either continuous or pulsed ...
1
vote
0answers
25 views

In the Leidenfrost effect why dropplets of water can travel uphill?

The Leidenfrost effect is a phenomenon in which a liquid, in near contact with a mass significantly hotter than the liquid's boiling point, produces an insulating vapor layer keeping that liquid from ...
8
votes
3answers
565 views

Why doesn't light affect a compass?

In our daily life a lot of photons of visible light, infrared and radio etc move around us. We know that light is an electromagnetic radiation. So why doesn't that electromagnetic radiation affect a ...
0
votes
0answers
12 views

Value of Planck scale

I read several times that the Planck scale is the energy scale at which the effects of gravity are comparable to the effects of the other fundamental forces. How can I show that this actually happens ...
0
votes
2answers
101 views

Derivation of Faraday's law using Lorentz force?

For a stationary loop of wire with a time varying magnetic field $\vec{B}(t)$ through it. Is it possible to derive Faraday's law, using only the Lorentz force $$\vec{F}=q \vec v\times \vec B \tag ...
0
votes
0answers
14 views

Water as heat source in a heat pump

Consider we have water flowing in a pipe, which is working as a hot source for a heat pump. We are able to know the temperature of the water in both ends of the pipe, yet we don't have information ...
0
votes
3answers
36 views

Torque on a disc?

In the following diagram: Point(c) is a going into the page and attached to the disc, Point(c) applies a torque($\tau$) to the disc, and it starts to rotate due to that torque. And if point(c) was ...
-4
votes
1answer
15 views

Is work done resultant of mass transformation?

high potential water -> Low potential water + Work done? mass = constant? what are the relational condition (energy, power, mass, force, pressure etc?) in both the forms (can we taken as both are ...
0
votes
0answers
16 views

Vertex of gauge boson interaction in an arbitrary gauge

Let's have interaction between some gauge boson (for example, $W$ boson) and some other field, for example, let assume $\bar{u}\gamma_{\mu}(1 - \gamma_{5})d W^{\mu} + h.c.$. Let's then use gauge ...
2
votes
4answers
71 views

In $1$-dimensional space, how would the gravity generated by an electron affect a photon moving away from the electron if the photon can’t slow down?

Suppose we had a universe obeying the same physical laws as our own. But it had only one spatial dimension (represented by the $x$ axis) and it was totally empty. There are just two point-like ...
0
votes
3answers
163 views

Is purple in visible light?

This isn’t a duplicate. I read those pages, but those didn’t answer my questions. Please watch this. Does visible light consist of red, orange, yellow, green, cyan and blue? No purple? My definition ...
0
votes
0answers
42 views

Description of charged circle with Dirac delta function in Cartesian coordinates [on hold]

I need to describe density of charge of uniformly charged circle ($x^2+y^2=R^2$; $z=0$, total charge $Q$) with Dirac delta function in Cartesian coordinates. In cylindrical coordinates it is: $$ \rho ...
0
votes
0answers
22 views

Light Intensity after refraction [on hold]

I have a bottle of water and I wanna measure the intensity of sunlight in different angles of sun radiation over the horizon (after refraction). Could you help me? radius of bottle : 5 cm Refractive ...
3
votes
1answer
345 views

Does a negative line tension in a 3-fluid immiscible interface make sense?

This question is inspired by this question/answer pair: Is this formula for the energy of a configuration of 3 fluids physically reasonable? Consider three immiscible fluids forming contact surfaces, ...
1
vote
0answers
50 views

Virtual particles and the scaling effect on valence quarks

Inside a proton there are 3 valance quarks. In addition, there is constant creation and annihilation of gluon, quarks and anti-quarks. The number of virtual particles we observe depends on how ...
-1
votes
0answers
21 views

Forces between neutrons and protons [on hold]

The nature of the electrostatic force and nuclear force between a proton and a neutron inside a nucleus is: (a)repulsive and attractive or (b) zero and attractive
0
votes
0answers
50 views

Electric fields and the propagation of information [on hold]

Let us consider a charged particle $A$ in a fixed position, and a second particle $B$ at some distance $r$ from $A$. Now $A$ and $B$ will feel a mutual force due to their respective electric fields. ...
0
votes
0answers
23 views

Accuracy of quantum mechanical algorithms

Is it possible for a quantum mechanical algorithm to ensure when the wave function collapses that the right answer will be obtained 100% of the time? For this, I am excluding processes such as ...
0
votes
1answer
34 views

Can an Atom be negatively as well as positively charged simultaneously?

For example there are three atoms- atom A, atom B, atom C. Atom A has 3 electrons, atom B has 4 electrons and atom C has 2 electrons. If we bring together atom A and atom B, in this case atom A is ...
0
votes
0answers
17 views

Simultaneity hypersurface, local rest frame in special relativity

I am reading the book "Special Relativity in General Frames" by Eric Gourgoulhon for its more axiomatic approach to flat Minkowski spacetime geometry. In this book, the author defines something called ...
1
vote
2answers
73 views
+50

Unit consistency

Does $^\circ\mathrm{C}^2$ have any physical consistency? I know that $\mathrm{K}^2$ is a valid unit even though I don't know in which context it can be used. But I feel strange about ...
1
vote
2answers
40 views

The equivalence between Heisenberg and Schroedinger pictures

In quantum mechanics, the two pictures of Schroedinger and Heisenberg are taken as equivalent, where in the former wavefunctions are time variants and operators are not, and in the latter it is the ...
0
votes
0answers
5 views

How to specify boundary conditions as function of curvature in dynamic elastic beam pde?

In this article (already mentioned in this question) the dynamics of a planar elastic beam with "cantilever constrains" (one clamped end and one free end) is modeled. Using the Euler-Bernoulli Beam ...
0
votes
0answers
14 views

SR: vector field and change of reference

If $U$ and $V$ are vector fields, then the derivative of $U$ along $V$ is the vector field $\nabla _V U$ with components $$\nabla _V U=V^b \frac{\partial U^a}{\partial x^b}.$$ I would like to verify ...
1
vote
1answer
40 views

The demise of the Tacoma Narrows bridge was casused by aeroelastic flutter. But isn't that just a special case of resonance?

Much of the research I've done on the Tacoma Narrows bridge disaster of 1940 attribute the collapse of the bridge due to aeroelastic flutter - not strucural resonance. But isn't aeroelastic flutter ...
1
vote
3answers
109 views

What is actually a conservation law?

Though in his lectures, Feynman didn't define conservation law, he did use it while explaining divergence theorem: [...] heat is conserved. That is, no heat is generated inside the material and ...
0
votes
1answer
18 views

Combination of current sources

Most books say that to connect sources in series, the current sources will be equal in magnitude. I really don't understand the meaning of this statement. What happens if you connect current sources ...
0
votes
1answer
33 views

Does a photon travel in all directions?

For example i am standing and a beam of light is passing in front of me. I am able to see that beam of light so does it mean that photons are travelling in all directions other than the photons which ...
2
votes
5answers
94 views

A reference frame is any coordinate system or just a set of Cartesian axes?

In Physics the idea of a reference frame is one important idea. In many texts I've seem, a reference frame is not defined explicitly, but rather there seems to be one implicit definition that a ...
0
votes
0answers
36 views

Chern Simons theory

I have a one question. i am studding Higher spin Theories Part 2(Gomez)http://arXiv:1307.3200.in section 1.2.2 of this he describes gauge algebras and about ISO(D-1,1) tells me:it admits a ...
2
votes
1answer
65 views

Why are log scales so common?

I am currently reading a very nice book on scales in physics. There is a discussion on the different physical scales which are based on the effect of the corresponding phenomena, the given examples ...
0
votes
2answers
34 views
0
votes
2answers
122 views

Heat flow in a hollow cylinder

Consider a hollow cylinder of different outer radius and inner radius and two different temperatures are maintained at the outer and inner surfaces such that inner temperature is higher. Because of ...
0
votes
0answers
21 views

mechanics, motion in a plane [on hold]

In the game carom, queen and striker are identicql qnd are placed as queen is placed at origin. Now striker is imparted a velocity Vo j(cap). Calculate the value of V1*V2, where V1 and V2 are ...
2
votes
5answers
91 views

Moment Of Inertia About Centre of Mass

Why is moment of inertia minimum about centre of mass of any rigid body?
1
vote
3answers
54 views

What is $E$ in the Planck-Einstein relation?

The Planck-Einstein relation was first given for photons $$E = h\nu$$ But later, de Broglie extended it to matter waves, and showed that it would hold for all particles as well. The $E$ for a photon ...
3
votes
1answer
59 views

Legendre transform for non-local Lagrangians, or Hamiltonian of non-local Lagrangian and their properties

This is sort of a multi-part question, mostly dealing with how to treat non-local Hamiltonians and how the corresponding properties of Hamiltonians work in a non-local framework. I proposed an example ...
2
votes
3answers
61 views

Is an atom charged after undergoing beta emission?

After beta emission, an atom's mass number remains the same while the number of protons increases by one. As far as I know, the beta particle (electron) is too energetic to be recaptured. If this is ...
-6
votes
0answers
41 views

Horrible crossword [on hold]

There's this physics crossword that is giving me a lot of trouble Water waves do this when they pass from deep to shallow water (7) _ e _ r _ _ _ Carries information by total internal reflection of ...
1
vote
2answers
4k views

Is water considered a substance with low friction or high friction?

Like, for example, rubber is a substance with high friction, as an object with neither high or low friction would easily stop on it, and wouldn't skid. Ice is considered an object with low friction, ...
0
votes
1answer
25 views

The AM (amplitude modulation) wave sidebands

I'm studying for A-level now..... I have read some other posts explaining how the sidebands generated after the carrier wave is modulated. So, if there is sideband frequency, the frequency isn't ...

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