Questions tagged [definition]
The definition tag is used in situations where the question is either about how some term or concept is defined or where the validity of an answer depends on a subtle definition of some term or concept used in the question.
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What is the difference between loudness, amplitude and volume?
i'm confused because some websites I've seen they are not the same, while my textbook says they're the same, and I'm trying to find the distinction between amplitude, loudness and volume.
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What is the difference between material time derivative and total time derivative of a tensor field? [closed]
I consider material coordintes as $(X_1(t),X_2(t),X_3(t),t_0),$ ($t_0$ arbitrary) and space coordinates as
$(x_1(t),x_2(t),x_3(t),t).$
$\textbf{Remark.}$ I am interested just in dim=3.
We consider a ...
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Strogatz's condition on definition of energy
In, Nonlinear Dynamics And Chaos, 2nd edition page 160, by Steven H. Strogatz, he writes
Let’s be a bit more general and precise. Given a system $$\dot x =f(x),$$ a conserved quantity is a real-...
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What is meant by optical density?
I’m trying to research about optical density for a school task, but the definitions online are confusing me.
From what I’ve gotten, optical density is:
how much the intensity of light is increased or ...
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GR and Riemann Surfaces -- does the complex plane have anything to do with it?
I have only the vaguest understanding of Riemann Surfaces -- my sense is that Einstein used them in General Relativity because of their shape.
But Riemann Surfaces I think are not just deformations of ...
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By what units is 'degradation to ozone layer' measured?
From Wikipedia:
The ozone depletion potential (ODP) of a chemical compound is the relative amount of degradation to the ozone layer it can cause, with trichlorofluoromethane (R-11 or CFC-11) being ...
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73
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Confusing definitions of EMF
I was studying about EMF (electromotive force) recently but had trouble connecting the two definitions of the topic. Here are the two definitions of EMF listed in my book (The book I've referred is: ...
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In layman’s language what is the difference between stopping potential and work function?
In layman’s language what is the difference between stopping potential and work function? It feels like both the things mean the same thing, if I am wrong please explain the things to me.
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What is charge on a fundamental level and what is it caused by?
On bigger bodies, I've learnt so far that charge is caused by a lack or excess of electrons or protons but when you look at an electron or proton, how are they charged? what is the cause of their ...
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Definition of entropy and microstates (Huang)
The definition of Boltzmann entropy given in Ref. 1 appears to be different from most sources I've seen up to this moment. Let me start from the latter: typically textbooks assume that in a given ...
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How to state that a function has a certain andament in a limit? [migrated]
Assuming we have a function $f(r)$ that has the following limit
$$ \lim_{r\to0} f(r) = \frac{5}{3 r^2} \,.$$
What is the correct symbol to express that the denominator goes like $r^2$?
Is the ...
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Confusion on the definition of dielectric permittivity
I don't understand how we're defining the dielectric permittivity, sometimes it's defined as the ability of the material to resist the electric field and sometimes as the ability to permit the ...
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Meaning of of inertial frames in special relativity [duplicate]
One of the postulates of special relativity is
The laws of physics are the same in all inertial frames
There is a mention of inertial frames in the postulate. But the predictions of relativity are ...
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How can I call a transformation where only the $z$-axis is modified by a function in each point?
What is called a transformation that maps $z \rightarrow |f(z)|\, z$, while the other axis stays the same? Is it a conformal transformation?
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Intensity of light - questions about the particle standard definition and concerning the units [duplicate]
In the $5.111$ MIT class, lecture $3$, it is written on the last slide "intensity of light = photons per second". Intensity is previously defined in the lecture as the square of the ...
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How to use the definition of a rank-$2$ tensor for this kind of examples?
Suppose that, a rank-$2$ tensor transforms as
\begin{align}
T'^{ij}=\frac{\partial x'^i}{\partial x^k}\frac{\partial x'^k}{\partial x^l}T^{kl}.
\end{align}
How to use this criterion to investigate if ...
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What is the connection between moments in probability theory and the moment of inertia?
My question arises as the moment of inertia (MOI) has been described as a second moment.
In my understanding if the MOI is indeed a second moment of a distribution of mass, this suggests the MOI could ...
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Photoelectron and electron in photoelectric effect [closed]
Could you please help me find some answers, as I have been stuck in this for a while and didn't get understandable answers.
what is the difference between the photo electron and an electron.
The ...
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53
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What exactly is equivalent resistance?
We all know the basic example of school with series and parallel resistors, so they might be a good place to start.
Given two terminals $A$ and $B$ from a circuit, if the current that exists $A$ is ...
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What does the $F$ in Newton's second law equation mean?
This is a super simple question: does $F$ represent the net force exerted on an object or the force it exerts on another object as a result of momentum? Say a ball is rolling. In this specific ...
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What are internal and external forces?
what is internal and external force? How do I decide what forces are internal and external?
in work-energy theorem and conservation of mechanical energy, do we consider internal, external, or both ...
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Why is warming food in the microwave work and not heat? [duplicate]
In Schroeder's An Introduction to Thermal Physics, heat is defined as the "spontaneous flow of energy from one object to another" and work is defined thermodynamically as any other transfer ...
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Second derivative of energy with $k$
In solid-state physics, we often encounter the velocity operator (e.g. this post) which the eigenvalues can be written as
$$
V^\mu(\vec{k}) = \frac{1}{\hbar} \frac{\partial E}{\partial k^\mu} \biggr|_{...
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Meaning of $n$-critical point
My lecture notes about field theory refer to a tricritical point as a point in which a continuous phase transition line meets a discontinuous phase transition line.
In the following it refers to a ...
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Is the definition of geodesics different if the electromagnetism is added to GR?
In plain GR, geodesic are defined by:
$$ \nabla_{u} u^{\,\mu} = 0 $$
where $u^{\,\mu}$ is the four-velocity of the particle.
Now, I don't understand if this holds true also in the electromagnetic case,...
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What is the relationship between Clausius Inequality and 2nd Law?
I am confused about the application of the 2nd Law for reversible and irreversible processes and cycles.
I want to know how the Clausius principle, the Kelvin-Planck statement, and the Clausius ...
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Clarifying the definition of pressure in statistical physics
I am studying David Tong's lecture note on statistical physics, and I have a question regarding the precise definition of pressure. I checked other postings in this community, but was unable to get ...
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Two values of Rydberg Constant
In my textbook I came across two values of Rydberg Constant:
\begin{align}
R&= 109\,677\ \mathrm{cm}^{-1}
\\
R_h&= 2.18 × 10^{-18}\ \mathrm J
\end{align}
when we are calculating energy of the ...
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What is $r$ in a metric signature in general relativity? If $v$ and $p$ are the time and spatial coordinates?
The Wikipedia article on metric signatures says that the signature of a metric can be written $(v,p,r)$, where $v$ is the number of positive eigenvalues, $p$ is the number of negative eigenvalues, and ...
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Rest Mass Energy
What exactly is the Rest mass energy? I know the usual goes Like it is total energy stored in mass $m$ that is in Rest. so for someone moving relative to the frame that the mass $m$ is in (a rest ...
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