Physical Definition and 1000 Threads

Difference between "physical reach" and "logical reach" of fibre optic Undergrad physics student here, working with fibre optic cables for my final year project, specifically to do with amplifying signals for fibre-to-the-home internet service. I understand the physical reach of fibre optics...

Hi, I am working on an Egg Drop Contraption as a Physical Science project. I need some help on a 1 page report I need to make. First, let me explain how my project will work so you can know how to answer my questions. I will have a box a bit bigger than the egg itself. The walls, floor, and...

Hi guys. I'm trying to get the idea of probability density for 1s hydrogen atom. I just don't understand that probability density reaches maximum at nucleus (r → 0) if the most probable radius where electron can be found is at Bohr radius according to radial probability (Which also states...

Hi, I found out this paper http://www.pha.jhu.edu/~javalab/pendula/pendula.files/users/olegt/pendulum.pdf with this animation http://www.pha.jhu.edu/~javalab/pendula/pendula.files/users/olegt/pendula.html At first there is written there, that the area of possible states in some range...

Could someone please help me understand the physical significance of TE and TM waves?

In some parts of the physics,sometimes it happens that the volume of a region of space or the area of a surface enters into a formula.In such situations,most of the time,the author argues that "although I have derived this formula for such a shape,it is independent of the shape of the...

Electric field of an electromagnetic wave incident on a metal accelerates free electrons, and these accelerating electrons then emit radiation opposite to the electric field of the wave, thus reducing the resultant amplitude in the forward direction. Radiation emitted in the backward direction...

hello, Help me to answer these questions: Give the physical meaning of Maxwell equations (equations in the general case). div D=ρ div B=0 rotE=-∂B/∂t rotH=∂D/∂t+J i have second question: What is the difference between conduction current and displacement current? thankyou

Hello , so the question is basically like that , I did some thinking about evolution and so I came to this question. Now the universe today with it's proton size and mass and particle charges , gravitational constant and all other things we know and yet don't know about , seems kinda precise...

Good evening guys, I have to decide whether to purchase Atkins or Levine for my physical chemistry learning? Personal experiences with the textbooks are encouraged.

Hello, I'm a dietetics student, and my course is really unclear about gluconeogenesis regulation, and exactly WHEN it happens. What my coursebook teaches me is that glycogenolysis is the main purveyor of energy during physical exercise, and it is triggered by LOW INSULIN, HIGH GLUCAGON and...

Hello, this is my first post on this forum so nice to be here, and I'll be very appreciative of any responses. My background is in acoustics, and hence my question is relevant to vibration propagation. The terms 'compression' and 'longitudinal' are both frequently used to describe the same...

This is something that has bothered me for some time, and I can't seem to find any threads on here about it. In a lot of my undergraduate courses in physics, we talk about integrating something physical to infinity. For example, in electrostatics, we talk about the work needed to assemble a...

Homework Statement Two identical thin rods, each with mass m and length L, are joined at right angles to form an L shaped object. This object is balanced on top of a sharp edge. If the L shaped object is deflected slightly, it oscillates. Find the frequency of oscillation. Here is a picture...

Homework Statement The Reaction; 2NO(g) + Cl2 (g) → 2NOCl (g) Is second order in NO and first order in Cl2. Five moles of nitric oxide and two moles of Cl2 were brought together in a volume of 2dm3 and initial rate was 2.4x10-3 moldm-3sec-1. What will be the rate when one half of the...

Hi, I'm a student working with my group to create a lab for our final lab project. Me and my teammates are stuck on how we should begin to set up the project. I attached 4 photos, one of the pendulum setup, one of the model of our pendulum setup, and two others of the lab sheet guide. The...

Hey! Where is the error in my reasoning?: The acceleration of the centre of mass in a swinging physical pendulum in simple harmonic motion is given by: ##M \ddot{\vec{r_{cm}}} = \sum m_j \ddot{\vec{r_j}} = \vec{g} M## If ##x## is the coordinate distance measured along the swinging-arc of the...

I am doing a small project on Gamma Ray Bursts. I am looking at a data set of around a dozen bursts which are observed at an angular offset from their host galaxies (My theory is that they are in dwarf galaxies orbiting the host galaxy). Say the average separation of these GRBs is 4...

Why when artists mix blue and yellow colors, we see green? What is the physical explanation of this?

I have done several exercises concering periodic potentials in crystal. Especially I did one, where I had to show that the Fourier component of the shortest reciprocal lattice vector (call this vector a) in the z-direction was zero. Now solving the problem was just about writing up the right...

Iam wondering whether 'infinity' has real physical existence or just a mathematical paradox? If it does have a physical existence why don't we come across any quantity which is physically eternal? Someone please help..

I don't know where to post this thread. Where could i download the book on mathematical methods in physical science by Mary?

For infinite square well, ψ(x) square is the probability to find a particle inside the square well. For hamornic oscillator, is that meant the particle behave like a spring? Why do we put the potential as 1/2 k(wx)^2 ? Thanks

Hello, I have this audio amplifier from Vivax AM 100. But it has somewhat weird problem. When you turn it on it starts buzzing but, not like buzzing on speakers but rather circuit starts buzzing, rattling noise. There is also like wax residue on the board, which i don't think its...

Hi, everyone. I once saw a science program with the danish astrophycisist Jens Martin Knudsen, who said that there exists seven absolutely fundamental constants of nature, and if one of these were changed ever so slightly, it would lead to drastic changes in the whole universe. So my...

This is not an assigned homework problem, just something I came across. It's in Griffiths E&M book. Also I apologize if my equations don't look right. They are showing up all weird on my computer screen. Homework Statement A point charge q of rest mass mass m is released from rest a...

Hi everyone, I was looking up Mohr's circle on planar stress and stress/strain relation and all that and I read a context on principal stress. It said that if there is both normal (tensile) stress and shear stress in a given area, then the principal stress at that location is greater than...

The photon field has two physical degrees of freedom (dof): its two transverse polarization directions. But what about non-abelian gauge theories? What about N massless spin-1 particles that transfom under SU(N), how do I count their degrees of freedom? Gluons, for example, are massless spin-1...

Source of Question J.N. Reddy states in Finite Element Method: "Variational forms of the laws of continuum physics may be the only natural and rigorously correct way to think of them. While all sufficiently smooth fields lead to meaningful variational forms, the converse is not true: There...

Consider we have a \Lambda type three level system, the one upper level is denoted by 3, and the two lower levels are denoted by 1 and 2. Assuming that the transitions between 1\leftrightarrow3 and 2\leftrightarrow3 are dipole alowed, while the transition between two lower states 1 and 2 is...

Are different electrical frequencies allocated to specific applications because of their properties or to regulate the spectrum so that each assigned frequency range is unique to one entity? I guess a related question is: Are we going higher in frequency ranges for things like automobile...

I'm having a little difficulty understanding the use of derivatives in Maxwell's equations. Eg. \oint E . dl = - \frac{d\varphi_{B}}{dt} this says that a changing magnetic flux in time, produces a potential difference (and electric field) in space? I noticed that its a full derivative, and its...

Standard Pauli spin matrices are: Sx: $$\left(\begin{array}{cc}0&1/2\\1/2&0\end{array}\right)$$ Sz: $$\left(\begin{array}{cc}1/2&0\\0&-1/2\end{array}\right)$$ The Sz eigenvectors are Z+ = (x=1,y=0) and Z- = (x=0,y=1). These yield eigenvalues 1/2 and -1/2 respectively. Similarly...

But can be modulated by bubbles. PLOS ONE: The Influence of Bubbles on the Perception Carbonation Bite

Background: I'm 22 year old and recently graduated with a B.S. in Electrical Engineering and landed a great first job which paid well with my own office. I was happy at first but then begin to realize that I didn't like what I was doing. If it were a matter of finding a different job, I...

"Paused" physical system Greetings, physicists and others, who just happen to understand physics. Something is bothering my mind again and I am hoping that some clarity will be given here. So, here is what I am thinking: if I Pause any physical system and, a bit after, sort of press "play" to...

Hi all, I am trying to hard to understand integral's transform. While an interpretation of Fourier transform is relatively easy to furnish in terms of signal decomposition and harmonics, it seems the "meaning" of Laplace transfrom is more subtle (in spite of the similarities between the two)...

When analysing the forces/energy transfers acting on a physical pendulum (albeit with a larger mass on the end, such as a grandfather clock...with a thick rod?) is it absolutely necessary to know the mass of the 'arm' (separate from the bob, as such)? Also, can the mass of the arm be calculated...

Hi all, I have a doubt regarding the physical significance of eigen vectors of the covariance matrix. I came to know that eigen vectors of covariance matrix are the principal components for dimensionality reduction etc, but how to prove it?

In conventional renormalization, for the self-energy, is it possible to make a subtraction from a point not equal to the physical mass? \frac{1}{p^2-m_o^2-\Sigma(\mu^2)-\Sigma'(\mu^2)(p^2-\mu^2)-...} Now define m_o^2+\Sigma(\mu^2)\equiv m(\mu^2) Then...

Hi, I'm going to be a senior in high school this coming year. I want to ask what exactly energy is and if it is physical? I know that we cannot see with our naked eye what energy is, but is it something physical and microscopic? What is it like? Thank you very much.

I think everybody here knows the equation that gives the potential of a point like dipole, but how does the field look like if you have e.g. a metal sphere with radius $R$ and a certain dipol moment, how does this potential look like?

Has anyone read..."Mathematics and the physical world '' by Morris kline? what are your views on it? not sure whether I should read it, or go to a specialized book,but I want to learn some basic physics or math from it.

Can someone explain what the expansion, rotation, and shear of a time-like congruence are physically?

Newton's laws, coulomb's law are all very neat but are they totally accurate? According to modern instruments which can measure up-to remarkable precision, do these laws behave perfectly? I haven't studied quantum mechanics yet but as far as I have heard it's all about probabilities ... we...

Homework Statement Find the period of a pendulum consisting of a disk of mass M and radius R fixed to the end of the rod of length l and mass m. How does the period change if the disk is mounted to the rod by a friction less bearing so that it is perfectly free to spin? The centre of the...

Hello. Im looking for a good scrap or junk yard that has good supplies for low prices, mainly electronics, science, aviation, military. Just a place that sells decent quality stuff that can be used for science related stuff. Like old radars, satellite dishes, monitors, medical electronics...

I've been trying for a long time to get an answer to the question, "What is the physics or mechanical explanation of contracting physical objects and the distances between them?" I understand that the phenomenon is theorized to depend on different observations from different frames of reference...

hi, please explain can by using suitable operator we can find any physical quantity- as by using hamiltonian on wave function we can find energies by the eigenvalues? thanks wasi-uz-zaman

Hi Does anybody know the physics meaning of the following equation \frac{\partial u}{\partial t}+\bar{U}\frac{\partial u}{\partial x}=D\frac{\partial ^3 u}{\partial x^3} Is there any physical system can be described by this equation? Thanks.