Physical Definition and 1000 Threads

  1. Entanglement

    Physical state of acids when they are ionized

    HCl(l) + H2O → H+(aq) + Cl-(aq) or is it HCl(g)+ H2O → H+(aq) + Cl-(aq) If HCL is liquid is it dil. or conc. ??
  2. J

    Physical Reason For Reduced Current In Step Down Transformer

    Hi everyone, I've been reading transformers and this question came in my mind. I'm unable to find a satisfactory answer. Why does the current increase in a step down transformer? I am aware of V1I1 should be equal to V2I2, but I was looking for a physical reason for the current to...
  3. J

    Calculate damping coefficient of dashpot from physical dimensions

    Hi all, I am trying to calculate the damping coefficient of a linear viscous dashpot/damper given the dimensions of the piston, and the dynamic viscosity of the damping fluid. I have found this calculator, but does anyone know the equation that it uses...
  4. P

    Cosmology vs. Physical Cosmology

    Is there a difference between cosmology and physical cosmology? The two have separate wikipedia pages which seem to say essentially the same thing. Also, cosmology is obviously a branch of physics, so is "physical" redundant?
  5. A

    Difference between physical reach and logical reach of fibre optic

    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...
  6. C

    Egg Drop Contraption: A Physical Science Project Report

    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...
  7. Absentee

    Physical meaning of probability density

    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...
  8. L

    Physical pendulum in phase space

    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...
  9. A

    Understanding TE & TM Waves: Physical Significance

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

    Volume and Area in physical equations

    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...
  11. D

    PHYSICAL explanation of light reflection by metals

    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...
  12. A

    What is the physical meaning of Maxwell equations

    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
  13. Crazymechanic

    Big bang , physical constants , possibilities

    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...
  14. I

    Physical Chemistry: Atkins or Levine?

    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.
  15. A

    When does gluconeogenesis kick in during physical activity?

    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...
  16. M

    What is the physical difference between compression waves and longitud

    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...
  17. V

    Integrating a physical quantity to infinity

    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...
  18. D

    Physical pendulum thin rods problem

    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...
  19. C

    Physical Chemistry- Rates and Kinetics

    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...
  20. C

    Lab Project - build a physical pendulum with the smallest period

    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...
  21. N

    Swinging periods of physical and simple pendelums

    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...
  22. F

    Physical conditions of nebulae/HII regions

    Hello to all! I'm trying to develop a routine (in ESO-MIDAS) similar to NEAT (Nebular Empirical Analysis Tool) or NEBULAR package from IRAF that, by inputting certain emission line ratios i could get the physical conditions of the nebula (like Te, Ne, ionic and elemental abundances). The thing...
  23. B

    Calculating physical separation of 2 sources at unknown angle.

    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...
  24. C

    Exploring the Physical Phenomenon of Color Mixing

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

    Fourier component crystal potential - physical significance

    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...
  26. V

    Infinity -just maths or any physical existence?

    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..
  27. ajayguhan

    Mathematical methods in physical scince

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

    What is the physical meaning for a particle in harmonic oscillator ?

    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
  29. B

    Audio amplifier physical noise+possible popped capacitor

    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...
  30. P

    Smallest set of fundamental physical constants?

    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...
  31. T

    Charge moving toward a conductor. Solution makes no physical sense

    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...
  32. L

    On the physical meaning of principal stress

    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...
  33. L

    Gauge fields - how many physical degrees of freedom?

    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...
  34. J

    Variation Formulations of Physical Laws: The Correct Formulation

    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...
  35. Z

    What's the physical interpretation of ρ for dipole forbidden channel?

    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...
  36. C

    Physical properties of frequency or regulation

    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...
  37. D

    Physical intepretation of derivative in Maxwell equation?

    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...
  38. J

    Physical significance of eigenvalues?

    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...
  39. Pythagorean

    Carbonation sensation is a chemical reaction, not physical

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

    Engineering Physical active Engineering careers?

    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...
  41. E

    Understanding Inertia: The Science Behind Paused Physical Systems

    "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...
  42. M

    Physical Interpretation of Laplace's Transform

    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)...
  43. H

    The physical pendulum - mass calculations

    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...
  44. dexterdev

    Physical significance of eigen vectors of Covariance matrix

    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?
  45. G

    Subtraction point not physical mass

    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...
  46. X

    Explain Energy (is it physical)?

    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.
  47. G

    Potential of a dipole with actual physical extension?

    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?
  48. T

    Mathematics and the physical world

    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.
  49. R136a1

    A physical description of some GR concepts

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

    Is There Perfection in Physical Laws?

    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...
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