What is Particles: Definition and 1000 Discussions

In the physical sciences, a particle (or corpuscule in older texts) is a small localized object to which can be ascribed several physical or chemical properties such as volume, density or mass. They vary greatly in size or quantity, from subatomic particles like the electron, to microscopic particles like atoms and molecules, to macroscopic particles like powders and other granular materials. Particles can also be used to create scientific models of even larger objects depending on their density, such as humans moving in a crowd or celestial bodies in motion.
The term 'particle' is rather general in meaning, and is refined as needed by various scientific fields. Anything that is composed of particles may be referred to as being particulate. However, the noun 'particulate' is most frequently used to refer to pollutants in the Earth's atmosphere, which are a suspension of unconnected particles, rather than a connected particle aggregation.

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  1. V

    Magnetic fields, charged particles and directions

    Homework Statement [/B] Charged particles with equal mass and identical initial velocities move through regions of space that may have magnetic fields. Rank the magnetic field in each case from greatest to least. For this question, fields out of the page will have positive values, while fields...
  2. C

    Understanding Cyclotron Oscillations Frequency

    I am having trouble making sense of the frequency of oscillations for a cyclotron. What I don't understand is, if a the voltage difference of the two dees is switched twice ( each time the particles are about to enter them), then why is the frequency of oscillation the same as the frequency at...
  3. M

    Number of closely packed colloidal particles in an aggregate

    Hello everyone This is sort of a geometry problem. I'm sure it has an easy answer but it just won't come to me. Here's my problem A close packed colloidal aggregate of smaller spherical colloidal particles can be thought of as small spheres within a sphere. I have the relationship...
  4. entropy1

    Why do ket vectors not have magnitudes?

    Why does the magnitude of a ket vector not matter? The motivation appears to be that a state vector only can decribe a particle, or no particle. But why shouldn't the magnitude of ket vectors not be used to represent the density of the particles, the average number of particles? I'm am fairly...
  5. S

    Gravitons and other subatomic particles

    Hi everyone. Am trying to find out how many gravitons are in a quark, or in a proton. Anyone here know, or can point to a reference that might have the answer? Thanks!
  6. N

    Calculation of particles by integral

    Hi, I would like to calculate total number of particles in one periodic wave-section whose radius varies by h(z)=1+A*sin(2*pi*z/L), where A is the profile amplitude and L is the wavelength of one wave-section. I thought, I will do by volume integration, say integral over V (volume of one...
  7. K

    How fast do particles need to travel to collide?

    I'm wondering, I always hear how particles in the LHC collide with huge energies, and I'm wondering: how much energy is needed for particles to collide? I mean, if the energies in the LHC are huge and the ones in the RHIC are less huge you have to be able to do it with even less energy, right...
  8. J

    Will 2 particles with paths crossed collide?

    Homework Statement The first particle A is starting at origin and it has a velocity vector with magnitude 10km/h and moves at an angle of 30 degrees relative to y axis. The second particle B is starting at (0,5) and it has velocity vector with magnitude 8km/h and moves at an agle of 60 degrees...
  9. jk22

    Can Quantum Particles Meet Everywhere on the Diagonal?

    Since particles have their own space i heard they cannot meet. But how about the origin if we see the axes perpendicular ?
  10. M

    Beta Particles -- range of energies?

    Hello, I was wondering if someone could explain to me what does it meant that a beta particle has a range of energies ? Thanks
  11. nuclearhead

    What functions of fields describe particles?

    I was thinking about the connection between fields and particles. For instance the scalar field Φ(x) and the field Φ(x)+a both represent the same scalar particle. Because the action ∫∂Φ∂Φdx^4 is unaltered and the propagator <0|[Φ(x)+a,Φ(y)+a]|0> is presumably the same. What about if we replace...
  12. F

    Natural frequency of 3 coulomb force bound particles in EF

    Homework Statement I was given a task to model (using Matlab) 3 identical particles in external field and find spectra of lowest system energy states using gradient descend method for each particle in the system. I did a run of 500 random generated coordinates and found this distribution...
  13. Garlic

    Creating a Cloud Chamber for Deflecting Charged Particles

    Hello and thanks for reading Homework Statement I'm in high school. I chose my yearly project in physics, and wanted to make a cloud chamber. The subject is "deflection of charged particles in a magnetic field", so I must set a magnet alongside the cloud chamber. I've prepared for it, bought...
  14. F

    How is the vacuum energy affected by nearby particles?

    When calculating the dynamics of a particle, we can use Feynman's path integral to determine the observables involved. This integrates over every possible path that the particle can take. We can even use it to calculate the vacuum energy of empty space. Now what happens to that vacuum energy...
  15. L

    Can scotch tape method get film size larger than particles?

    Hi there, I am preparing to use the scotch tape method to get hex-Boron Nitride thin film from hBN powder. As far as I know, the available particle size for hBN is 10 um at most, is it possible for me to get hBN thin film using the peel off method with size larger than 10 um? If so, what is the...
  16. hdp12

    Problem Check: Equilibrium of Particles

    Homework Statement A continuous cable of total length 4 m is wrapped around the small pulleys at A, B, C, D. If each spring is stretched 300 mm, determine the mass m of each block. Neglect the weight of the pulleys and cords. The springs are unstretched when d=2 m. The Attempt at a Solution I...
  17. N

    Difference between Delta particles and protons and neutrons

    I am trying to figure out the difference between Δ0 and Δ- and the proton and neutron since both appear to have the same combinations of up/down quarks. Deltas have isospin 3/2 and spin angular momentum 3/2 whereas protons and neutrons have isospin 1/2 and spin angular momentum 1/2. I'm...
  18. A

    Light -- how light particles can penetrate through glass?

    how light particles can penetrate through glass?
  19. K

    Diffraction wavelength of particles in moving frames?

    Here's a question I cannot seem to comply with my understanding of Quantum Mechanics. The characteristic wavelength of a particle is responsible for diffraction interference fringes, which is part of the wavefunction solution to the schrodinger equation. But the wavelength of a particle is...
  20. Ahmad Kishki

    Exploring Wave-Particle Duality of Water

    We know that water waves are the simple harmonic motion of particles transferring their energy along the wave, but why do we say that water waves are not just particles, given their particle origin? Suppose then we say that a wave is just a collection of particles, then how do we explain the...
  21. Jewish_Vulcan

    Describe PE of Particles in a Gas

    I understand why there is KE in the particles of a gas but I cannot really visualize the where the PE is coming from.. please straight forward answers!
  22. hdp12

    Equilibrium of a Particle: Determining Forces in Cables and F for a 4-kg Lamp

    Homework Statement I am stuck on this problem for my mechanics class. Please help me. Determine the force in each cable and the force F needed to hold the 4-kg lamp in the position shown. Hint: First analyze the equilibrium at B; then, using the result for the force in BC, analyze the...
  23. hdp12

    What is the weight of block D in this equilibrium of particles problem?

    Homework Statement Here is the problem that I am stuck on in my mechanics class. https://lh4.googleusercontent.com/ygXVjNfI4iP8xVpEjhxXZlWlDqg_VrM2gCVFLyomOVwWCfcLU78mIcPEc7hEzUqBoACIiQ=w1210-h506 Homework Equations F=-kx The Attempt at a Solution See the attached picture of my work...
  24. E

    System of 2 particles: why is the wavefunction a product?

    I am trying to solve for the energy of 2 non-interacting identical particles in a 1D infinite potential well. I want to do it as much "from scratch" as possible, making sure I fully understand every step. H = -ħ2/2m * (∂2/∂x12 + ∂2/∂x22) Hψ=Eψ ∂2ψ/∂x12 + ∂2ψ/∂x22 = kψ, where k=-2mE/ħ2 I got...
  25. LarryS

    Are there particles with zero spin?

    Are there any elementary particles with zero intrinsic spin? Thanks in advance.
  26. A

    Assumption on central forces between two particles

    Homework Statement Consider Newton’s force law for two particles interact through a central force F12(r1',r2',u1,u2), where by Newton’s third law F12 = -F21. m1(d^2r1/dt^2) = F12(r1,r2,u1,u2) m2(d^2r2/dt^2) = F21(r1,r2,u1,u2) A. Show that Newtonian mechanics is form invariant with respect...
  27. P

    What is the most efficient way to produce charged particles?

    hello! what is the most efficient way to produce charged particles? like protons (H+) or electrons or ions or anything like that thanks!
  28. I

    Deriving equations for pressure & number density for centrif

    Homework Statement Consider particles in a gas centrifuge. This device is used to separate gases of different molar mass by rotating a cylinder at high rates. Derive two equations: one for the pressure (P) and one for the particle number density (nv) as functions of M, r, w and T, where r is...
  29. W

    Movement of particles on vibrating plate

    So our professor showed us wave patterns on a vibrating plate, by sprinkling powder over it. I'm curious as to why it behaved as it did.The powder moved to nodes, but I'm not sure why. I think it just gets bounced around until it lands on a node, which is stationary, so it then stays there. Is...
  30. L

    Find Magnitude & Direction for acceleration:

    Homework Statement : Block B has acceleration of 4 m/s2... Relative acceleration of block A w/ respect to B is 4 m/s2. Find magnitude & direction of accel for A?[/B] Homework Equations a_A = a_B + a_A/B[/B]The Attempt at a Solution a_A = 4 +4 = 8 m/s2 <-- 8*cos(20) = 7.52 (x-component)...
  31. Coffee_

    [QM] Addition of spin for normal and identical particles

    1. Problem: Consider the composed system of two particles of spin ##s=1## where their angular momenta is ##l=0##. What values can the total spin take if they identical? What changes when they are distinguishable? The Attempt at a Solution : The problem I have here is incorporating the fact...
  32. X

    Why is work negative when we push two opposite particles tog

    The below is what has me confused. It's essentially stating that if we apply a force on a positive charge and push it close to a negative charge, our applied work is negative. Why is this? I am confused about it because W = Fd and both F and d have the same direction. The potential energy U...
  33. C

    Dark matter -- particles or modified gravity?

    What is the evidence for dark matter being new particles as opposed to some modified form of gravity?
  34. G

    Massless Particles: Force Bearing & Propagation Speeds

    It looks to me like all the massless particles so far discovered may be force bearing particles, there being 3 of them. Am I right? If so can it be said that forces propagate at the speed of light whilst what we might think of a tangible particles cannot? I did post this question on another...
  35. S

    System with two particles with spin QM

    Homework Statement Two particles with spin ##S_1=1## and ##S_2=1## are in our system. For wavefunction of the first particle we know that ##S_{1z}|\psi _1>=\hbar |\psi _1>## while for the second particle ##S_{2x}|\psi _2>=\hbar |\psi _2>##. a) Find wavefunction ##|\psi _1>## in basis with...
  36. Coffee_

    Idential particles, postion wavefunction for fermions.

    1. In griffiths the following is written down in the chapter of identical particles: ##\Psi(\vec{r_{1}},\vec{r_{2}})=\pm \Psi(\vec{r_{2}},\vec{r_{2}})## Where it's + for bosons and - for fermions. However in class we have seen that for two electrons in the spin singlet situation the POSITION...
  37. BiGyElLoWhAt

    Carrier particles and E-Field Propagation

    A thought experiment that is a consequense of a question someone asked in my particle physics class: We place an isolated electron. We wait 10 years, and place a half ring of electrons (spaced far apart from each other, but uniform) 10 LY away from our central e. Will our charges move? If so...
  38. B

    Understanding virtual particles

    what is the correct understanding of a virtual particle? the popular science books would have us believe that a virtual particle magically pops up out of the woodwork, steals some energy and then puts it back before it ( the particl) disappears. Like a thieving employee who steal $100 out of the...
  39. R

    Ultrasound absorption by particles in water

    Hi All, I am in need to calculate the ultrasound (20MHz) absorption of particles (polystyrene of size 15 microns) in water. I tried to search in the internet, but couldn't find any simple analytical expressions. Can someone please help me ! Thanks in advance! Regards, Radel...
  40. M

    Split someone into Subatomic Particles?

    So if I somehow constructed a Freeze Ray that could lower someone's or something's temperature to absolute zero, would they split into subatomic particles ?
  41. D

    What is an Exchange Particle? A-Level Physics Explained

    I really want to understand the answer to this question. Q: What is an exchange particle? A: A virtual particle that let's force act between particles in an interaction. This answer was given in my A-Level textbook but I can't for the life of me decode what it means. For example in beta minus...
  42. Invutil

    Are photons imaginary particles?

    Since an electron generated a negative charge around itself and can push other electrons around itself, waves can travel through electrons. These are electromagnetic waves. But quantum theory proposes that the pushes between electrons happen in discrete packets. Electromagnetic packets called...
  43. Bendelson

    Exploring Factors of Radiation Production from Cosmic Ray Particles

    I've heard of the muons and electrons that constantly hit Earth's surface in cosmic rays coming from extra terrestrial particles that break up in Earth's atmosphere but I was curious what factors played a role in the type of radiation produced from these particles in the atmosphere (i.e. More...
  44. N

    Separation of subatomic particles within a capacitor

    I've recently taken to understanding capacitors and capacitance. If I understand them correctly they are what store electrical charge or electrical energy. I don't quite understand their purpose though, do they keep the breadboards from overloading with power but keeping little pockets of...
  45. T

    Virtual particles are just math (MWI and MUH)

    I was reading a lot that "Virtual particles are just math..." and many physicists for some reason get angry explaining it. But I suspect this point of view is interpretation-biased and is outdated for 3 reasons listed below: 1. The (mathematical) discovery of Quantum Decoherence had provided a...
  46. J

    Time for ring of equidistant particles to collapse (gravity)

    (I assume that the three section headings below form the template referred to below) 1. Homework Statement n identical equi-distant particles are distributed equi-distantly around the circumference of a ring of radius r in space. Each particles is of mass m, so the total mass of the ring is...
  47. S

    Relativistic relative velocity of particles

    Homework Statement In a given inertial frame two particles are shot out simultaneously from a given point with equal speeds u at an angle of 60 degrees with respect to each other. Using the concept of 4-velocity or otherwise, show that the relative speed of the particles is given by ##u_R =...
  48. A

    Virtual particles coming into existence

    from what i understand they pop into and out of existence because + 1 - 1 = 0 and because quantum mechanics... and that's the same reason we have matter in the first place, right? because we had anti matter and matter (from virtual particles, right?) in the beginning of the observable...
  49. S

    Ways to put subatomic particles in indeterminate state

    1 what are the various methods/ways, besides quantum entanglement, to put, some of, the photon properties an indeterminate state? 2 what are the various methods/ways, besides polarizers or measurement, to put the photon properties a determinate state?
  50. D

    Particles - subparticles - subsubparticles

    Why recent particle physicists don’t consider models of particles (quarks, leptons) built from more light subparticles? Is there problems of principle or the available experimental data don’t need similar models?
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