# Questions tagged [unit-conversion]

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### 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 ...
102 views

### Units conversion - quanta/cm$^2$/s and photons/cm$^2$/s

Can you tell me if there is any difference between these 2 units? $\log \mathrm{quanta/cm^2/s}$ vs $\log \mathrm{photons/cm^2/s}$ Thanks
106 views

### Geometrized units in Wald

I am trying to follow a derivation in this paper from Wald Specifically, at the end of the paper, just under Eq. 4.7 there is given the equation $$Q/m \leq 2 B_0 m$$ where $Q$ is the system ...
312 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 ...
85 views

### Converting width in $\rm GeV$ to lifetime in years

I am trying to reproduce the results of this paper (https://arxiv.org/pdf/2003.03285.pdf). In particular Eq (25) and (26). I would like to convert the proton decay width (given in units of $\rm GeV$) ...
175 views

### Conversion formula between attenuation coefficient (cm^-1) and (dBcm^-1MHz^-1)

So, I was presented in class the fact that (at least in Ultrasound), attenuation coefficients $\mu$ can be expressed in units $\text{dBcm}^{-1}\text{MHz}^{-1}$ as opposed to the form I was used to; ...
35 views

### Grasping systems of units

Perhaps it's that I've grown up with the SI system of units, but there's something about other unit systems that doesn't sit well with me. For example, Coulomb's law in Gaussian units can be written ...
128 views

### I'm confused about electric flux?

In a previous physics class, I learned that the electric flux was $\vec{E}\cdot\vec{A}$ (dot product), and hence the unit is $Nm^2/C$. But in my electromagnetics book, it says the unit is Coulomb, and ...
32 views

### Dimension scaling of a model hamiltonian system?

I have a model 2dof double well potential Hamiltonian given as $$H = P1*P1/2 + P2*P2/2 + V(Q1,Q2) ,$$ where $$V(Q1,Q2) = -2*Q1^2 + Q1^4 - Q2^2 +Q2^4 +0.4*Q1*Q1*Q2*Q2 ,$$ there is no units are ...
375 views

### Are Heaviside-Lorentz unit and Gaussian unit natural units?

I am studying electromagnetism and have encountered the Heaviside-Lorentz unit and Gaussian unit. In these unit systems, the constant $c$ keeps occurring. For example, the Maxwell equations are of ...
90 views

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### Question about Schrodinger equation in atomic units vs in SI units

In SI units, we see that the Schrodinger equation can be written as \begin{align} i\hbar\partial_t \Psi= \left(-\frac{\hbar^2}{2m_e}\Delta_x+V(x)\right)\Psi \end{align} whereas, in atomic units, we ...
37 views

### How to convert this expression from natural units to those used experimentally

I cannot for the life of me do the correct conversion of the following expression I derived for two flavour neutrino oscillation. I need to convert the expression from natural units ($c = \hbar = 1$ ) ...
34 views

### How do you convert from Townsend Unit (Td) to kV/(cm bar)?

I have found a conversion online which says 1Td = 2.829 V/(cm Torr) and 1Torr = 0.001332 bar and with this ; 1Td = 0.3768 V/(cm bar) However from literature for SF6; 362Td = 86.3 kV/(cm bar) where ...
51 views

### What is the relation of Permittivity of free space (ε₀) with esu unit of charge in cgs system?

In the CGS system the Coulombs law is defined as $F=\frac{Qq}{r^2}$ with the constant $k=1$ which was equal to $\frac{1}{4\piε_0}$ in the MKS system. The thing that allows this equation to be valid ...
99 views

### Natural unit conversions within HEP

In HEP, with the $$\hbar = c = 1 \;.$$ We have $$\hbar c = 200 \;\mathrm{MeV \cdot fm}$$ 1 second is equivalent to $10^{-25}$ GeV. How these relations are used to convert seconds to GeV, GeV to ...
66 views

### How do Becquerels relate to Grays?

I understand that becquerels are SI units for curies, and that curies are a measurement of radioactive decays per second. I understand that gray is the measure of uncharged ionizing rays in a sample ...
21 views

### Spectral irradiance unit conversion (Jansky)

I'm a bit confused between two units for spectral irradiance, specifically $W/sr/m^2/nm$ and $\mu Jy/"^2$, which is analogous to $W/sr/m^2/Hz$. It seems to me that I need some sort of spectral ...
22 views

### Equivalences for mCi doses and cGy?

I was searching a lot and could only find dosages for curing cancer and allowed emission, but no Iridium 192 dose that could be given internally through brachy sources been found, lets say a 700 cGy ...
25 views

### For vibrations in continuous beam, what is the unit of eigenvalue?

I have been solving a fourth order euler bernoulli differential equation to solve for vibrations of a continuous cantilever beam. When I verified for them using Comsol eigenvalue solver, it gives me ...
76 views

### Conversion between mass units

I am enrolled in a course related to physics, and converting between mass units is so tricky for me. I always treat in my work only in SI units and maybe MKS units, at level of weights, I find it easy....
141 views

### How do I convert $W/(mK)$, $W/m^2$ and $W/(m^2K)$ to the same “dimensionality” and unit?

How do I convert $W/(mK)$, $W/m^2$ and $W/(m^2K)$ to the same "dimensionality" and unit? $W/mk$ is thermal conductivity. $W/m^2$ is heat flow density related to one unit. $W/m^2k$ is heat transfer ...
59 views

### Finding the generated magnetic field of a Hall generator

I've been using a Hall generator to generate a particular magnetic field by applying a current. I need to work out what field this corresponds to in Tesla. All I have to go on is what's in the photo ...
302 views

### What are the actual electromagnetic units in the foot-pound-second (FPS) system?

So I've been reading this Wikipedia article, and I came across the cited note that someone has derived the electromagnetic units for the FPS system. However, I can't find that publication so does ...
59 views

### How many calories are burned by lifting 80 kilos once?

After some calculations i figured it was something like 192 kilocalories but it sounds a bit too much so im not sure if i did the right calculations. What i did was calculate the work and then convert ...
70 views

### Interpreting impulse value “c kg”

I have a small question about a physics exercise concerning the relativistic relationship between energy and momentum. The exercise says: We have 2 objects with rest mass 8 kg. We shoot the objects ...
38 views

### In the process of probability of two flavor neutrino, how does the factor $1.27$ comes from?

Up so far I have been working on deriving probability for two flavor neutrino and have consistent results with wikipedia or textbook. But I have some trouble with deriving some factor $1.27$. \...
267 views

### How to Convert Dimension of $R$ constant of Air (J/Kg.K)?

Example) (P=nRT/V) in this equation P=nRT/V, The final dimension is achieved should be a function of pressure, But I can not understand this dimension in final (mol.J/Kg.Liter). when use in R ...
73 views

### Easy unit conversion in Kerr metric

I would like to use Kerr metric in Boyer-Lindquist coordinates in geometrized units with mass of the black hole normalized to $M=1$. I am embarrassed to admit, but I can't seem to figure out how to ...
43 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 ...
163 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 ...
77 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 $\frac{decays}{s}$ ...
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In the TOV equation of state of neutron star if we take central pressure and central energy density in Mev/fm^3, then in what will be the unit of radius in the graph of pressure vs radius. Usual we ...
77 views

### Capacitor's Charge

I see the formula of charge on capacitor's plate is $C=\frac{KA}{d}$, where $K$ is the dielectric constant and $A$ is the area of the capacitor. Now some sources indicate the unit of $A$ as square-...
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 \$...