A convention is a set of agreed, stipulated, or generally accepted norms. It typically helps common efficiency or understanding but is not required, as opposed to a strict standard or protocol.
Questions tagged [conventions]
1855 questions
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Why was carbon-12 chosen for the atomic mass unit?
The atomic mass unit is defined as 1/12th the mass of a carbon-12 atom. Was there any physical reason for such a definition? Were they trying to include electrons in the atomic mass unit?
Why not define the amu as the mass of one proton or neutron…
Dieblitzen
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93
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7 answers
Why is it "bad taste" to have a dimensional quantity in the argument of a logarithm or exponential function?
I've been told it is never seen in physics, and "bad taste" to have it in cases of being the argument of a logarithmic function or the function raised to $e$. I can't seem to understand why, although I suppose it would be weird to raise a…
sangstar
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84
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6 answers
Why does public mains power use 50-60 Hz and 100-240 V?
Is there a physical reason behind the frequency and voltage in the mains electricity? I do not want to know why exactly a certain value was chosen; I am rather interested to know why that range/order of magnitude was selected. I.e., why 50 Hz and…
SuperCiocia
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Why is the charge naming convention wrong?
I recently came to know about the Conventional Current vs. Electron Flow issue.
Doing some search I found that the reason for this is that Benjamin Franklin made a mistake when naming positive and negative charges.
There is even this little comic…
GetFree
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73
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Should zero be followed by units?
Today at a teachers' seminar, one of the teachers asked for fun whether zero should be followed by units (e.g. 0 metres/second or 0 metre or 0 moles). This question became a hot topic, and some teachers were saying that, yes, it should be while…
Vidyanshu Mishra
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What are the proposed realizations in the New SI for the kilogram, ampere, kelvin and mole?
The metrology world is currently in the middle of overhauling the definitions of the SI units to reflect the recent technological advances that enable us to get much more precise values for the fundamental constants of nature than were possible when…
Emilio Pisanty
- 137,480
62
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2 answers
Difference between $\Delta$, $d$ and $\delta$
I have read the thread regarding 'the difference between the operators $\delta$ and $d$', but it does not answer my question.
I am confused about the notation for change in Physics. In Mathematics, $\delta$ and $\Delta$ essentially refer to the same…
Yuruk
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48
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1 answer
Why is the partition function called ''partition function''?
The partition function plays a central role in statistical mechanics.
But why is it called ''partition function''?
Arnold Neumaier
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45
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2 answers
Identification of particles and anti-particles
The identification of an electron as a particle and the positron as an antiparticle is a matter of convention. We see lots of electrons around us so they become the normal particle and the rare and unusual positrons become the antiparticle.
My…
John Rennie
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43
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7 answers
Why is gravitational potential energy negative, and what does that mean?
I usually think of gravitational potential energy as representing just what it sounds like: the energy that we could potentially gain, using gravity. However, the equation for it (derived by integrating Newton's law of gravitational…
41
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2 answers
Square bracket notation for dimensions and units: usage and conventions
One of the most useful tools in dimensional analysis is the use of square brackets around some physical quantity $q$ to denote its dimension as
$$[q].$$
However, the precise meaning of this symbol varies from source to source; there are a few…
Emilio Pisanty
- 137,480
39
votes
4 answers
Can units be plural?
I was in a conversation with my senior engineer where he kept on insisting that we can use plural when we write down any unit. I argued that it is not the 'common' practice or even throughout my whole academic career (unfortunately) I haven't found…
Ahmed
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Why is the potential energy equal to the negative integral of a force?
Why is the potential energy equals to the negative integral of a force? I am really confused with this negative sign. For example, why there is a negative sign in the gravitational potential energy and what does it mean?
I read that the negative…
Omar Ali
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35
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5 answers
Why do we use the electron volt?
Why do we use the electron volt?
Why did it come to be the electron volt and not, say, just a prefix of the joule, like the nanojoule?
Does the electron volt represent anything particular as far as the mathematics goes? I am guessing that it does,…
Benjamin Rogers-Newsome
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35
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2 answers
Symbols of derivatives
What is the exact use of the symbols $\partial$, $\delta$ and $\mathrm{d}$ in derivatives in physics? How are they different and when are they used? It would be nice to get that settled once and for all.
$$\frac{\partial y}{\partial x}, \frac{\delta…
Steeven
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