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2answers
259 views

Numerically solving 2D poisson equation by FFT, proper units

The 2D Poisson equation is: (1)$$\frac{d^2\varphi(x,y)}{dx^2}+\frac{d^2\varphi(x,y)}{dy^2}=-\frac{\varrho(x,y)}{\epsilon_0\epsilon}$$ And in $k$-space it is in form of: (2)$$(k_x^2+k_y^2) ...
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2answers
295 views

A change of units in Bethe formula

I'm reading through the following paper: Monte Carlo simulation of non relativistic electron scattering by W. Williamson and G. C. Duncan. In the following paragraph, I want to know how to arrive at ...
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1answer
19 views

Recalculating lux from EV

I have to calculate amount of light from IR emmiter. The only equipement, that I can use is Sekonic Light Meter like this one: http://www.ebay.com/bhp/sekonic-l-358 The problem is that i need to have ...
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0answers
305 views

How to convert Richter magnitude scale to approximate TNT?

I know the Richter magnitude scale is often used for measuring the strength of earthquakes. At the same time, explosive/destructive releases of energy are often quoted in equivalent amounts of TNT. Is ...
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0answers
65 views

What unit system puts a bunch of powers of ten in Maxwell's equations?

In what unit system can we get the Maxwell equation in the following form (section 1.2 from Lewin's book Advanced Theory of Waveguide) $$\nabla\times \vec E = -10^8\mu \frac{\partial \vec H} ...
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0answers
20 views

How to understand/derive Eq 5.5 in Geiner's Quantum Mechanics - An Introduction?

Geiner's Quantum Mechanics - An Introduction has an unnumbered equation above Eq. 6 in section 2.4 discussing density -- not sure if it is energy density -- of radiation: ... $$dE/dV = E/V =a ...
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0answers
49 views

Geometrised Units

I am curious as to how to express a area units in geometrised ones. I was reading on wikipedia and saw that when angular momentum is converted into geometrised units, it is expressed as a dimension of ...
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0answers
52 views

Noise of a fiber optic gyro

I have not much experience with noise handling or calculations, furthermore in my researches couldn't find a similar problem, so here is my attempt: Having a fiber optic gyro that is rated with a ...
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0answers
178 views

Galaxies and projected radius vs arcmins

I have two sets of data (globular clusters), one for the Andromeda Galaxy and one for the Milky Way. I want to compare the distribution of globular clusters between the two galaxies according to ...
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0answers
915 views

FPS to MKS usage issues

I'm currently taking a high school physics class and we're doing friction problems now. I've been doing the ones that use MKS perfectly well, but when the problems start to use the FPS system, I'm ...
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0answers
27 views

Units in Plasma Physics

What are the units people use in plasma physics? I am having hard time converting an equation from an old paper to SI units. I saw temperature being defined in $eV$. I assume this is $eV/k_B$ with ...
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0answers
27 views

Natural units conversion

Now, in this question, in the accepted answer, to convert from Kelvin to cm^-1, he directly multiplies by the SI equivalents of $k/\hbar c$ (although in the link, he converts cm^-1 to K). However, ...
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0answers
36 views

Heavyside Lorentz units and Gaussian units

What is the relation between Heavyside Lorentz units and Gaussian units? From this Wikipedia article, I noticed there are $4\pi$ difference between them, but my TA wants more. Is there other ...
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0answers
38 views

Conversion from Curies to current of alpha particles

Is the following conversion correct from microCuries to Amperes? $\mu Ci=(1$x$10^{-6}Ci)$ x $(\frac{3.7x 10^{10}Bq}{Ci})$ x $(\frac{2e}{\alpha})$ x $(\frac{C}{e})$ Becquerels are $\frac{decays}{s}$ ...