# Tagged Questions

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### What is dimensional units/quantity and dimensional state

First, I am not a native English-speaking student so I am not good at physics definitions in English. I participated in the MIT e-learning course on classical physics. The 1st lesson is about 3 ...
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### Definition of Ohm in SI basic units in words

One way Wikipedia defines Ohm is (this is also teached in school): $$1\Omega =1{\dfrac {{\mbox{V}}}{{\mbox{A}}}}$$ They describe this definition in words, too: The ohm is defined as a resistance ...
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### Why does Coulomb's constant have units?

I think of Coulomb's constant as a conversion factor (not sure if this is correct). Kind of like how you would do calculations in kg and then times it by the conversion constant to convert your answer ...
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### Could velocity be taken as fundamental instead of time?

In physics time and length are taken as fundamental in the SI system and, as it seems, in the thinking of physicists. Could one instead take velocity, with c as its unit, together with length as ...
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### Dimensional analysis of magnetic energy: dimensions of µ0 and H

When calculating the energy difference between the normal and the superconducting state in a superconductor at zero magnetic field, the result is as follows: Now I'm quite confident of this result, ...
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### The units of gain and number of atoms in population inversion in a laser

I am following my university course notes on amplification in laser media, and have come across expressions for the gain of a medium, but the notes are not exactly rigorous... The expression given for ...
### What physical quantity has SI unit $\mathrm{kg}/\mathrm{m}$?
What physical quantity has SI unit $\mathrm{kg}/\mathrm{m}$? For example, the physical quantity with SI unit $\mathrm{kg}\cdot\mathrm{m}/\mathrm{s}^2$ is force $F$ and the physical quantity with SI ...
In log-plots a quantity is plotted on a logarithmic scale. This got me thinking about what the logarithm of a unit actually is. Suppose I have something with length $L = 1 km$. $\lg L = \lg km$ It ...