Questions tagged [terminology]

Use this for questions relating to the proper use of physics terminology or nomenclature.

Filter by
Sorted by
Tagged with
3
votes
2answers
536 views

What's the difference between linearly polarised and plane-polarised waves?

To explain polarisation, my book gives an example of a transverse wave in a string, and explains as: Since each point on the string moves on a straight line, the wave is also referred to as a ...
0
votes
1answer
449 views

Difference between yaw angle and slip angle

What's the difference between slip angle and yaw angle (speaking about cars)? It seems they both are the angle between the actual direction of travel and the direction towards which it is pointing.
3
votes
2answers
3k views

What is the difference between the diffusion equation and the heat equation?

I know that the diffusion equation is a more general version of the heat equation. But what is the exact difference informally?
0
votes
0answers
20 views

Latent Heat and Ordinary Heat?

We have a name for the thermal energy associated with the change of potential energy during a phase transition. Unless I'm very mistaken, we call this latent heat. Here we have $Q=mL$. But what ...
0
votes
1answer
158 views

When should we consider “reverse Heisenberg” evolution of operators?

In Quantum Mechanics, the Heisenberg evolution of an observable $\hat{o}$ is defined as $$ \hat{o}(t) = U(t,0)^{\dagger} \hat{o} U(t,0) $$ where $U(t,0)$ is the unitary time-evolution operator from ...
0
votes
1answer
52 views

What's the difference between repulsive Delta function and Attractive Delta Function?

What's the difference between repulsive Delta function and Attractive Delta Function? I need to clear the concept. Please note that I know what's the Delta function.
5
votes
1answer
212 views

What's the difference between a time crystal and a system undergoing periodic motion?

What's the difference between a time crystal and a system undergoing periodic motion? My understanding of a crystal is that it is a rigid body with a spatially periodic structure. Is any system ...
1
vote
0answers
169 views

What is the different between Poisson Nernst–Planck and Poisson Navier–Stokes in the Electrolyte?

I am now studying about electroosmosis flow phenomena which is governing by the Navier-Stokes equation and Poisson equation. By combine these two equation we can describe the electrolyte flow velocity ...
1
vote
2answers
206 views

Tensors defined by transformation laws are tensors at a vector space or tensor fields?

In Physics it is common to see tensors defined by transformation properties relating components of the object in different coordinate systems. There is, however, two ways we can think of a tensor: a ...
4
votes
1answer
117 views

Constants of Integration In Hamilton-Jacobi theory

I have had this confusion for a while now. We solve the Hamilton Jacobi equation, $$H+\frac{\partial S}{\partial t}=0$$ Say we get a solution $S(q,\alpha,t)$ where $\alpha$ is a constant of ...
0
votes
0answers
13 views

How does the term “time-integrated flux density” apply to the effluence of a stream of atoms on a surface?

I just edited this answer to read Kapton (again from SMAD), will degrade at a rate of 2.8 μm for every $10^{24}$ atoms/m$^2$ of atomic oxygen time-integrated flux density encountered, with silver ...
0
votes
3answers
76 views

Is there a name for the unit “Ampere meter”?

Motivation: I'm doing a homework problem involving a rod sliding freely down a pair of parallel conducting rails. I've got a quantity of unit $\mathrm{A \cdot m}$ and want to know what I should name ...
0
votes
1answer
38 views

Is there any synonym to the “flaring out condition” of travesable wormholes?

Given the knowledge of Einstein Field Equations, the one could ask if it is possible to connect asymptotically regions of a given spacetime, such that a time-like curve is possible to transit between ...
3
votes
1answer
63 views

Historical meaning of action

In the Feynman lectures, it is stated Also, I should say that $S$ is not really called the ‘action’ by the most precise and pedantic people. It is called ‘Hamilton´s first principal function.’ Now ...
0
votes
2answers
35 views

Physics terminology: Can a light beam be displaced?

Say you have a rotating mirror and a fixed laser beam pointed towards the mirror such that the reflection of the beam changes direction. Can you say that the light beam has been displaced? Why or ...
0
votes
3answers
43 views

Kinematics: Circular Motion

What is the difference between angular velocity and angular speed? Is angular velocity after one complete rotation zero? Is the magnitude of angular velocity always equal to angular speed?
-4
votes
2answers
109 views

Why is the ångström not a metric unit? And why is the ångström spelt with the Scandinavian letters “å” and “ö”?

The website here http://unitsofmeasure.org/ucum.html tells us whether every unit is metric or not. Metric units can be multipled by a power of 10 and can be combined with a prefix. 1 ångström is ...
0
votes
0answers
12 views

Is there a noun for a material that absorbs, scatters and luminesces?

I know Luminophore is used for molecules or nanocrystals which absorbs and emit light, and Scatterer is used for materials which scatter light (elastically or inelastically). I suppose it would be ...
4
votes
1answer
526 views

Does effective theory have the same meaning in particle and condensed matter physics

I have a naive question about the meaning of effective theory in particle physics and condensed matter physics. In particle physics, from what I know, the effective theory comes from the Wilsonian ...
6
votes
3answers
2k views

What is the difference between the meaning of “state space” and “configuration space”?

What is the difference between the meaning of "state space" and "configuration space"? I'm only familiar with the first, and when I look up the second I can't tell the difference.
0
votes
1answer
34 views

What is meant by homogeneous in $x$ in $n$'th degree?

I'm reading about classical mechanics by Goldstein, and in the section about Hamiltonian mechanics it is stated that in the expression: $$H(q,p,t)=\dot{q}_ip_i-L(q,\dot{q}, t)$$ the Lagrangian ...
1
vote
1answer
150 views

What is the difference between scattering and absorption/emission?

As far as I know, scattering occurs when light excites the atoms or molecules to their higher energy state(virtual state for scattering) followed by emitting photons corresponding to energy ...
1
vote
2answers
381 views

The meaning of covariant but not manifestly covariant

What is the most general meaning of the expression covariant, but not manifestly covariant? Suppose I have a general (local) change of coordinates, $x^{\prime} = f(x)$, on an $(n+1)$-dimensional ...
0
votes
0answers
39 views

Elongation of a simple pendulum

One of the questions on this weeks question sheet asks for the maximum elongation of a simple pendulum. The pendulum is set in motion on the moon with f = 0.5Hz. What is meant by the elongation of the ...
18
votes
9answers
6k views

The instant an accelerating object has zero speed, is it speeding up, slowing down, or neither?

This problem is from Khan Academy. Specifically for the blue point circled in red, the answer is that at this blue point, the object is neither speeding up nor slowing down. When I think about the ...
0
votes
0answers
10 views

Use of “rate function” as rate over density

Heggie (1975) uses the term rate function to express the ratio of the rate $R$ of some event (for example the dissociation of a given binary star by the interaction with a passing field star) with the ...
2
votes
4answers
3k views

Difference between homogeneous and uniform?

Homogeneity means that something is the same in every point in space, whereas isotropic means that there is no directionality. Uniformity implies there is "no variation". But what is actually the ...
0
votes
1answer
44 views

Difference between discharge tube and capacitor

I did search this on google but didn't get satisfactory results. Can you tell me difference between capacitor and discharge tube? "**Discharge tube has its gaseous medium at very low pressure but ...
0
votes
2answers
80 views

What is the External force? [closed]

In a vacuum, a uniform electric field of strength $E$ is applied in the positive x-axis direction. When you carry a charged particle with a positive charge $q$ from $A$ to $B$, seek the work that the ...
0
votes
2answers
340 views

What's the relationship between probability amplitudes and amplitudes of a wave?

Amplitudes or probability amplitudes are the complex coefficients of the linear combination of states which represent other quantum physical states. The amplitude of a wave can be interpreted as a "...
0
votes
2answers
88 views

Complex numbers in physics [duplicate]

Can someone please explain the origin of complex numbers in physical values. For instance, denoting a plane wave with Euler's identity and also the complex relative permittivity? Thank you.
1
vote
1answer
49 views

What is a quantum system?

I heard that a wavefunction applies to a quantum system. But what is a quantum system? I am new to quantum mechanics, sorry for asking a basic question.
4
votes
1answer
338 views

Classification of field types in QFT

In Classical Field Theory fields are sections of bundles over spacetime. In particular we almost always consider vector bundles. Some examples are: Scalar fields: these are sections of the trivial ...
22
votes
4answers
150k views

What exactly is the difference between radiation, conduction, and convection?

Okay, so everywhere I've read, I hear the main difference is the requirement of a medium. But for example, if you take the case of heat 'radiating' from a red-hot iron, isn't that actually convection ...
0
votes
1answer
45 views

The difference between exact solution and analytic solution

My mother tongue is not English so I am confused with the difference between exact solution and analytic solution. Are these the same?
9
votes
4answers
211k views

What is the difference between phase difference and path difference?

The path difference is the difference between the distances travelled by two waves meeting at a point. Given the path difference, how does one calculate the phase difference?
1
vote
1answer
36 views

What is a free parameter?

Soft question here, but I was wondering just what exactly free parameters are? I have a murky understanding on the concept but I would much appreciate someone shedding some light on the matter. Is ...
1
vote
2answers
113 views

Why is the 1-dimensional wave equation called like that when it seems to be 2-dimensional?

The wave equation in one dimension traveling along a string is: $$ \frac{∂^2y}{∂x^2} = \frac1{v^2} \frac{∂^2y}{∂t^2} $$ but this equation has 3 variables $x, y,$ and $t$, shouldn't it be in 2 ...
0
votes
0answers
22 views

In particle physics, how should we call a model with several Higgs boson : Higgs multiplet?

In Higgs physics of the Standard Model, there is only one Higgs. The Higgs belong to a Higgs doublet. After electroweak symmmetry breaking, there is only one remaining Higgs, and 3 Goldstone bosons. ...
0
votes
1answer
36 views

What's the name for “middle” principal axis of inertia?

See this question for some context about the stability of rotation of a body around different axes. I am now trying to say that the rotation around the middle axis is very unstable, without using ...
-2
votes
1answer
68 views

Feynman screwjack problem

What is a thread? How does he know you need to turn the handle "around" 10 times? From where does the 126 inches come from? I thought Feynman explanations were easy... Let us now illustrate the ...
2
votes
2answers
50 views

Fermat's Principle: no first-order change in time?

I was reading the chapter on Fermat's principle in the Feynman lecture series. The principle is stated along these lines: "The correct statement is the following: a ray going in a certain ...
2
votes
1answer
52 views

What does topologically stable mean?

I am working on an article about skyrmion manipulation and it is written that those particles are "topologically stable particle-like spin configurations that carry a characteristic topological charge ...
-1
votes
1answer
53 views

Noun for particles that are quantumly entangled

What will we call particles that are in a "quantum entanglement" kind of relationship? not looking for examples (like thingamatrons can participate theoretically in quantum entanglement); rather the ...
1
vote
2answers
322 views

Friction force in rolling motion

In rolling without slipping motion we know that the friction acting is static friction and so we treat it as an unknown while solving equations of dynamics. Question: Is the static friction during ...
0
votes
0answers
20 views

What is recessional nonlocality?

In laymen’s terms, what is recessional nonlocality? I understand recessional means to recede or retract away, and (correct me if I’m wrong) I understand locality has something to do with quantum ...
1
vote
2answers
441 views

What is the linear attenuation coefficient and how does it relate to interaction probability?

I have misunderstanding the linear attenuation coefficient (L.A.C) concept. As known, L.A.C is depend on absorbed medium and energy of incident radiation. Supposing, L.A.C= 100 cm-1, how can this ...
1
vote
1answer
94 views

What is *diagonal* long range order?

I have seen this question about off-diagonal long range order in superfluids. What’s the difference and the significance between long range diagonal and off-diagonal long range order?
2
votes
1answer
97 views

What are $U(n)$ or $\mathbb{Z}_2$ quantum spin liquids?

Quantum spin liquid is a state of matter in which spins are correlated and fluctuate even at zero temperature. My question is about these terms in general. When we say that a state or a quasi-...
2
votes
1answer
90 views

What is a rigid wave function?

The London equations prior to BCS that describe superconductivity require assuming the wavefunction describing the superconducting pair of electrons to be rigid. I've been looking all over trying to ...

1 2 3 4 5 32