Questions tagged [unit-conversion]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
0
votes
1answer
31 views

How to convert dBm/MHz to dBm?

I wonder if we can convert dBm/MHz (eirp) to dBm? For example: What is the equivalent of -30 dBm/50MHz as dBm? Edit 1: I wonder if power spectral density (dBm/MHz) can be expressed in dBm. In EN 302 ...
2
votes
1answer
54 views

How to remember Maxwell equation in Gaussian units? [closed]

I know Maxwell relation in MKS unit $$\begin{cases}\nabla\times E=-\frac{\partial B}{\partial t},\\ \nabla \times B = \mu_0 \epsilon_0 \frac{\partial E}{\partial t} + \mu_0J,\\ \nabla\cdot E = \frac{\...
0
votes
1answer
37 views

Physical quantities conversion

searching for experimental values of the consumption rate of $O_2$ by tumor cells I found an article that measures the rate in the units of measure $$\frac{mol}{cell\cdot s}.$$ The actual measurement ...
0
votes
0answers
8 views

How to make the Coulomb potential return energy per mole?

I'm trying to adjust an electrostatic potential curve obtained via DFT calculations to the Coulomb potential equation to obtain the charges for a given atom. I know that the coulomb potential is given ...
0
votes
2answers
355 views

Is there a general algorithm for conversion of units?

I'm not exactly sure where the best place to put this, as it's more of a general question about dimensional analysis. I decided I was tired of having to convert units all of the time, and was not ...
0
votes
1answer
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 ...
0
votes
1answer
51 views

A book or a PDF with ALL the conversions between units. Does it exist?

I was wondering if there is a book (or a pdf) with all the conversion factors, equations etc., and also between different systems like all the conversions between the SI and cgs and so on. It's so ...
1
vote
1answer
99 views

Why does $\epsilon_0=1$ in CGS units?

This Wikipedia article gives a table of certain constants in different systems of units. I noticed that in Gaussian and electrostatic CGS the value of $\epsilon_0$ equals the dimensionless $1$. I ...
0
votes
1answer
19 views

Converting units, for the magnetic moment

I found, that magnetic moment is measured by $\rm J/T$, and equals magnetization times volume: $$\vec{m}=\vec{M}V$$ Magnetization, also equals magnetic susceptibility times external magnetic field: $...
0
votes
2answers
68 views

How can I see that newton-meters are equal to coulomb-volts?

I know $\mathrm{J} = \mathrm{N\ m} = \mathrm{C\ V}$, but what if I want joules expressed in SI base units of $\mathrm{kg}$, $\mathrm{m}$, and $\mathrm{s}$? This is trivially easy if I use $\mathrm{N\ ...
1
vote
1answer
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 $\rm GeV$) ...
0
votes
1answer
41 views

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 ...
5
votes
4answers
827 views

Why do (kilo)watt-hours double-count units per time?

A watt is defined as 1 joule per second and is therefore a measurement of energy transfer over a period of time. A kilowatt-hour is a measurement of energy equal to one kilowatt sustained over a ...
0
votes
1answer
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 ($c = \hbar = 1$ ) ...
0
votes
1answer
36 views

Kepler law expression in other units [closed]

Consider the Kepler law : $$P^2=\frac{4\pi ^2 a^3}{G(m_1+m_2)}$$ I am asked to express this law in astronomical unit, solar mass and years. The solution of this problem states that in this case $G=4\...
0
votes
1answer
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 ...
1
vote
1answer
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 ...
1
vote
1answer
36 views

Derive the conversion factor from SI to Geometric units [closed]

In the geometrized system of units, $G = c = 1$. This directly gives us the definitions for second and kilogram in this system, as $1\:s = c_0\:m$ and $1\:kg = G_0c_0^{-2}\:m$, where I have used the ...
1
vote
1answer
74 views

How should units be treated?

First sorry I don't know how to properly use this page yet. Secondly, in a electricity problem I've found the following expression: $$(q_1*q_2)/r_1 +(q_1*q_3)/(r_1+r_2)+(q_2*q_3)/r_2=0\tag{1},$$ and ...
1
vote
2answers
71 views

How can one measure the speed of light in MPH?

so, how can we actually do it? Its well known that the speed of light is a certain number of miles per second, but if its never been tested, how do we get that number?
0
votes
1answer
44 views

Converting units when $c=G=1$

In my homework assignment it is written that to convert from time to length you need to multiply by $c$, and to convert from mass to length you need to multiply by $G/c^2$, however I dont entirely ...
0
votes
3answers
4k views

Ideal gas formula $PV = nRT$ in Celsius scale

I was wondering how to re-write that ideal gas formula $PV = nRT$ applicable to Celsius or Fahrenheit scale. I know $R$ has unit $\frac{\mathrm J}{\mathrm{mol\cdot K}}$ and $T$ has units in K, that ...
0
votes
1answer
148 views

Need help in calculating the pull on string in kg when moving weight on horizontal bar

need your help. I realized today, if you do not practice it becomes hard to understand simple concepts even you were once a science student. :( I have attached a picture to help make the problem ...
3
votes
1answer
2k views

CGS Units to SI Units

This may be a stupid question but I am having trouble getting the same result in CGS units as I would if I used SI units for a unitless calculation. I have to calculate $E_\mathrm c=\frac{m_\mathrm ...
0
votes
2answers
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 ...
0
votes
1answer
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 ...
0
votes
0answers
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 ...
0
votes
2answers
65 views

Units associated to PID Terms [closed]

I am trying to understand PID Controllers .. I don't understand very well what Physical Quantity is associated to each PID Term, The Block Diagram of PID is this: the PID Equation is this: $$ u(t)=...
6
votes
2answers
683 views

CGS Units for Magnetism

Why does the formula for magnetic field force include the speed of light in the denominator in cgs units? Where does the extra $c$ go in SI units?
0
votes
2answers
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 ...
0
votes
1answer
43 views

Unit Conversion with Temperature and Mixed Dimensionality

So, I understand the relationship between K(Kelvin), R(Rankine), C(Celsius), and F(Fahrenheit), and the complications of converting between them (i.e. varying meaning of zero). However, when ...
1
vote
1answer
77 views

Banana vs Brazilian Nuts Radiation

Looking online I can find that the BED (Banana Equivalent Dose) is around 0.1uSv, but Brazilian Nuts can have up to 444Bq/kg. I know both of those foods are safe, I just wanted to understand how ...
0
votes
1answer
48 views

How to convert $V/A$ (Volts/Ampere) data to $T/s$ (Tesla/seconds)? [closed]

I have a list of time domain electromagnetic data that I need to invert, but the equipment provides the data in V/A and the software to invert need it in db/dt [T/s]. Would someone help me, please?
0
votes
3answers
166 views

How to measure vacuum permittivity?

In this question, the first answer (though I don't completely understand that answer) states that $\epsilon_0$ is the proportionality constant in Gauss' law. If that's the case why isn't it assumed to ...
0
votes
1answer
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 ...
0
votes
1answer
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 ...
1
vote
0answers
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; ...
0
votes
1answer
158 views

How is the Time Derivative of the the Electric Field Equal to the Current Density in Gaussian Units?

The microscopic form of Ampere's law with the Maxwell addition in Gaussian units states, \begin{equation} \nabla \times \vec{B} = \frac{1}{c} \left ( 4 \pi \vec{J} + \frac{\partial \vec{E}}{\partial ...
0
votes
1answer
45 views

MW@kV conversion

First, I'm sure this question is way too easy for this forum but I didn't find a better one. I'm having an argument on the following and we'd like to settle it officially. On a website about Diesel-...
2
votes
1answer
144 views

Confusion on the cgs, Heavside-Lorentz and SI system

I am very confused about three measuring systems: cgs, Heavside-Lorentz (never used) and SI ...
0
votes
1answer
665 views

Dimensional Analysis in Electromagnetism (SI vs Gaussian-cgs)

Looking at Konopinski's formula for conjugate momentum (in the comment after equation 3 of "What the Vector Potential Describes"): $\mathbf{p}= M \mathbf{v} + q\mathbf{A} /c$ it is plain enough that ...
0
votes
2answers
228 views

Unit confusion - How Pressure and Volume combines to Joule

Imagine some helium in a cylinder with an initial volume of $1$ liter ant initial pressure of $1$ atm. Somehow the helium is made to expand to a final volume of $3$ liters, in such a way that its ...
0
votes
1answer
63 views

Express the total mass of the galaxy in solar masses

I have the following problem: "The Sun has an orbital speed of about 220 km s−1 around the center of the Galaxy, whose distance is 28 000 light years. Estimate the total mass of the Galaxy in ...
-1
votes
1answer
289 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 $...
0
votes
3answers
2k views

Why is 1 newton meter=.225 lbs force?

This is a general question regarding force (mass x acceleration). I understand 1N =1kg mass x 1 m per second sq) all this basically tells me is that the force is proportionally increased and ...
1
vote
1answer
54 views

How to convert $\rm kg/m^3$ to $\rm J/m^3$ for natural gas and biogas? [closed]

I want to convert from mass density to energy density: Natural gas has a density of $0.8\: \rm kg/m^3$. Biogas has $1.15\:\rm kg/m^3$. I want to convert them into $\rm J/m^3$ so that I can ...
0
votes
0answers
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 ...
0
votes
0answers
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 ...
0
votes
2answers
454 views

When using Planck's constant, how do I know when to use electron volts or joules?

Planck's constant may be written as 6.63 x 10^-34 Js or 4.14 x 10^-15 eVs right? But how do I choose which one I should use to figure out an answer to a question?
2
votes
1answer
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

1
2 3 4 5 6