Si Definition and 142 Threads

Does anyone know of a dimensional formula for the Coulomb in SI that does not involve amperes as in A*s? I am looking at some equations and the dimensional analysis is leaving me with C (Coulomb unit charge) and left over m, kg, s to various powers. Just curious if anyone has come across some...

Hey guys, I'm currently working on a chemistry setup and we're building some protocols. We decided that every communication on the protocol between two devices will be in SI units. However, for a data descriptor I plan to use 4 bits per standard SI unit. This means that units for variables can...

All, please help me refine, restate, explain, understand, expand, add, remove, answer the below statements/ questions. Thanks in advance. 1.) Voltage is considered a scalar quantity. (J/C in SI Derived Units) which is a magnitude of energy per coulomb...no direction with this example. Some...

G(x)=3x * (1-2x^2)^-1/3 See attached photo for my proof, I'm sure its not right.

What qualifies for being called a fundamental quantity and having its own fundamental unit? For example length is considered fundamental quantity and it has a unit of meter. But Area isn't considered fundamental. Is it because we know area can be CALCULATED by multiplying the length of the two...

Hello, I am fairly new to using psychrometrics, so I am hoping that this is a fairly simple solution. I was going back through some old problems and wanted to spot check a few calculations. In the process I converted the units on one of the problems and the enthalpies were not matching up. I...

Hello, Could someone help me finish this train of thought? This is how we think in SI units: First, just because we like the value of 1 Ampere as it is now, we choose the force between two parallel conductors to be exactly 2×10^{-7}N= const ×\frac{1A×1A}{1m} Then, purely as choice, we decide...

Hello, I was reading about a comparison betw. Gaussian and SI units and the author states "The main advantage of Gaussian units is that they make fundamental physical issues and theoretical relations involving electromagnetic phenomena more clear." Would someone know - is the advantage...

Homework Statement When an object falls through air, there is a drag force that depends on the product of the surface area, A (m2), and the square of the velocity, in (m/s). The equation is Fdrag = CAv2. The metric unit of force is the Newton, or (N). 1 N = 1 kg*m/s2. What are the units...

hi, why electric current is a SI base unit - why not couloumb?

Are the SI units for pressure N m^2 or is it N m^-2?

Homework Statement Represent the following combination of units in the correct SI form using the appropriate prefix km*mN Homework Equations k = 10^3 m = 10^-3 The Attempt at a Solution km * mN = (10^3)m * (10^-3)N = m*N = Nm Have I done this correctly?

Homework Statement This is the question Still think that unit conversion isn't important? Here is a widely publicized, true story about how failing to convert units resulted in a huge loss. In 1998, the Mars Climate Orbiter probe crashed into the surface of Mars, instead of entering orbit...

The base units are meters kg and seconds, right? So are some equations meant to use a different set, like cm kg minutes or something. And is it always assumed to be si unless told otherwise?

Can anybody explain... what makes silicon indirect band semiconductor? thanks in advance Vani

As I know, electrical conductivity is a second rank tensor. So in a cubic structure, there is no orientation dependence of electrical conductivity (isotropic). But how come Si has higher electron conducitivity along [001] and hole conductivity along [110]?

A few years ago, I was reading about a contest open to everyone. The question was something like : if you were on a desert island, with unlimited natural resources, and access to a book with the most accurate values of properties for various natural things (i.e. gravitational acceleration on...

Hi guys I m new to his forums o I hope I post this in the right place. I have a questions about the 11 dimension. As I saw some documentaries about M theory, it seems our universe was created by colision in the 11 dimension. So I was wondering how does it looks like. At the beginning of big...

So I understand that converting between CGS and SI units is no easy task when you look at the general form of each equation in electromagnetism, as you can't simply relate the two systems given they have different ways of looking at what is a derived unit and what is fundamental. But once you've...

Homework Statement It is estimated that a particular diffuse hydrogen cloud has a particle density of 3e7 cm^-3, and the temperature is 150 K. Calculate Jeans mass. Homework Equations Jeans mass is given by: (5kT/GmewM(H))^(3/2) . (3/4∏p)^(1/2) where k = boltzmanns constant =...

Hi. I'm asked to convert 2 year into the SI Unit seconds: Known: 1 Hr = 3600 s 1 Day = 86400 s So using a calculator... 1 yr = 365*86,400 = 31,536,000 I want to express the answer in scientific notation: Because the lesser number on has 3 significant digits, the scientific...

How can I convert an equation in units where hbar = c = 1 into an equation with hbar and c in SI units? I searched around a bit and wasn't able to find anything (I'm probably not asking the right question). Is there some general way to do it rather than just intuition from having seen the...

I have attached a pic which really explains the formula and context of the problem. I'm guessing a gravitational effect passes for physics... I am trying to convert the formula in (b) below into feet. If I could reproduce the answer with English units, I could move on and apply the...

I have attached a pic which really explains the formula and context of the problem. I am trying to convert the formula in (b) below into feet. If I could reproduce the answer with English units, I could move on and apply the formula to other situations, but the multiplicity of English...

Homework Statement Determine the density of fictional planet in SI units from the information Homework Equations Planets mass 1.28x10^22 Kg divided by radius 1.12x10^3Km = 1.14x10^25 Kg/m3 The Attempt at a Solution My answer seems all wrong, the SI unit should be in Kg/m cubed. Is...

Homework Statement I am reading about electrodynamics, and in different formula, there is a SI form and a Gaussian form. Homework Equations What is the relationship in the different unit system for c or B or E and other relative variables? The Attempt at a Solution sometimes...

Homework Statement This a trajectory problem. A ball is launched from ground level at a unknown angle. ( ∅o= ? ) at an unknown velocity ( Vo = ? ) The ball travels 20 meters in the x direction and 25 meters up in the y direction. At this point (20,25) the ball hits a wall and a -45 angle...

The deciBel is probably the most commonly used unit for sound, but why isn't there an SI unit? Also, what is a logarithmic unit? Thanks.

Homework Statement If speed, v, of an object depends on time, t, according to the equation v = A + Bt + Ct^4, what are the SI units of A, B, C? Homework Equations v = A + Bt + Ct^4 The Attempt at a Solution For this, I've not known where to start, so I've be plugging in the variables...

Is it possible to see twins in Si under an optical microscope?

why carbon can form polymers and sillicon not? though both are tetra valent. explain this based on its orbital and bonding energies

The definitions of other units that doesn't depend on the kilogram are somehow constants, like the speed of light, the second, the meter (defined with respect to the previous 2) and so on. However when it comes to the kilogram, we're still using a definition of 1889. It's definied as the mass...

I recently noticed that in Silvaco Atlas (device modeling software), the default bandgap of silicon is given as 1.08 eV. This is at 300 K, no bandgap narrowing, and no other secondary effects - it is default. However, most (all?) of the modern references (e.g. Sze, Streetman, Pierret) give the...

After the discovery of the speed of light, it may have made a bit of sense to redefine the meter as \frac{1}{300,000,000} the distance light travels in a second. I understand that larger units like the light year may have been distorted a bit, and that conversions would be required for such...

Some help with Si Unit conversions :) Homework Statement 762 Mg/m to ng/µm Homework Equations Si unit conversions The Attempt at a Solution How do I know where to place the variables? Can someone give me a tut or written explantion on how to do this?

Hi, I fabricated a very simple back-gate FET. I used highly Boron doped (so, P-type) Si wafer as a gate and then, grown SiO2 thermally as a dielectric. And, deposited N-type semiconductor followed by Au/Cr deposition as electrodes (source and drain). And I measured Ids-Vds and Ids-Vg. The...

i have a basic question about the natural frequency of a system. for a mass (M), spring (k constant) undamped system the natural frequerncy is: w_n=sqrt(k/M) the units of w_n according to a lot of resources i found on the internet & textbooks are [rad/sec], my question is why? if i use...

Homework Statement If a 2000 lb car with a velocity of 88 ft/s has by my calculations a kinetic energy of 240 kJ. But for a 909kg car with a velocity of 26.73 m/s I calculate 324.7 kJ. Same velocity, same mass, different energy calculation. Homework Equations English units: Kinetic...

Hi, I was curious as to what webers and teslas measure. As I read up on them I was able to speculate that teslas measured a magnetic fields dimensions and webers measured a magnetic fields strength; obviously though, this is a mere speculation: so please correct me if I am mistaken. Thank you

The SI unit "henry" Is a "henry" only produced by magnetic induction, in which case would produced one volt that allows the induction of one ampere per second?

I wanted some help in finding out the time taken for a differential mass of gasoline being burnt in the cylinder during the power stroke. Also, does it depend on the residual temperature of the mixture? I tried to find it out through Arrhenius equations but am having a problem finding out...

I would like to express an SPD matrix A as: A = sI + B where B is also SPD, or alternatively as: A = I + B what constraints need to be imposed on B? Please let me know if this question is mot appropriate for this forum. thanks, Russ

Hii... I have a powder that consists of Si, SiO2, Fe3O4, FeO and Fe. I really want to measure the conversion of Si to SiO2. Anybody know what kind of instrument or method that can be used to measure the composition?

Hello, I have the problem, from Sze' book, tunneling current, what is m*? I want to konw the value of it. The m* has many reference, how do I select? My interested device is diode that was doped with Boron and Phosphorus for p-n junction. Thank very much.

Hi, Looking for the SI Notation practices for Direct Current and Voltage Direct Current. We commonly use DC and VDC, but I wonder if that's correct per SI. I've looked through several guides and pdf's of SI Notation, and haven't yet been able to find the answer. Any help you can...

Homework Statement Got a charge of 2CGSEm need to find it in SI Homework Equations 1C=2.998*10^{9}CGSE The Attempt at a Solution Just a plain question, I get q\approx6.66*10^{-10} Is that correct?

Homework Statement Convert the following as full (decimal) numbers with standard (base) SI units: 86.6 m The Attempt at a Solution I thought I could just change it to 8.66x10^1 then just add the 10^-3 because of the milli to make it 8.66x10^-2. But I'm wrong so could someone help me?

In doing some research, I cam across an equation for instantaneous radiated power, with the CGS units "erg/(sec rad cm)", rad being radians (not rad the unit for radiation exposure). Try as I might, I'm not able to come up with a way to convert it to the SI units for watts. Does anyone know...

Hi, I'm trying to calculate the minimum mass of a star, where M=PV³/2πG The values I've been given are V=400km s^-1 and P=34.4 hours. Does this mean that I have to convert these values to SI units, i.e. give the values in terms of metres and seconds rather than km and hours? This would...

what is the average air to fuel ratio in spark ignition engines?