Si unit Definition and 26 Threads

Hello - I am trying to understand the physical meaning the undergirds the Debye length as it pertains to different unit systems. I understand that fundamentally its the distance at which the distribution of ions doesn't differ by more than the effect of k_B*T from the rest of the solution...

Hi, I love physics since school, but after years I forgot a lot of what I studied. I hope this forum will help refresh my memory. Also I built a web converter application to convert different measurement units and this forum can be really helpful for me to promote it and keep improving it. Thanks

I was wondering: what would be the value of Vacuum Permettivity in the case 1 meter (say 1m") would be defined as the distance we nowadays see as 1,10 meters. At first this looks easy: ##\varepsilon0 = 8.8541878128 \cdot 10{^{12}}## F / m with normal meters so ##\varepsilon0" = \varepsilon0...

When we talk about engines on automotive industry (cars, motorbikes, trucks, etc.), we often refer the power produced by such engines by horsepower. But when we talk about electricity, the power is measured in kilowatts. Despite the former case is highly popular, why isn't horsepower considered...

Homework Statement Is N/m^2 a si unit I know Newton is and meters but togeather are there or is m^2 Homework Equations The Attempt at a Solution N/m^2 m^2

I am computing force between two magnetic poles each of one unit pole (in emu) and situated one centimeter apart. In electromagnetic units: ##F_{dyne}=\dfrac{p^2}{r_{cm}^2}=\dfrac{1^2}{1^2}=1 dyne## where ##p## is pole strength in emu In SI units: ##F_{N}=k_A \dfrac{P^2}{r_m^2}=10^{-7}...

Why is the quantity "information" missing from the SI system? Also, if they did add it, do you think it would be added as a base unit or dimensionless derived unit?

Hi I have a value that is 10.7 mJy, that I need to convert to SI units. I thought it would be 1.7*10^(-2)*10^(-26) but that might be wrong? Then I have a flux value, kappa, of 2 cm^2.g^(-1) that needs to be converted to meters and kilogram. I thought it was 2*10^(-7) m2/kg, but that might be...

Hi, I'm doing an experiment to get my silver CREST award, in which I've created a mechanical paper plane thrower. I have thrown various types of plane, but all with the same design. The thrower uses a 9V battery, but is more like 6 now. The thrower has two motors, each which take 70mA. The...

Dear friends, As you know, in CGS units we have vacuum permeability as unity (1). so H=B and we use Oersted for H. on the other hand, in SI, permeability is (4 x pi x 0.0000001) and we use Ampere per meter for H. unfortunately after trying for couple hours, I couldn't derive the algebra of...

Just simple questions and I need clarifications why is that your answer please. 1,602 ×10^−19 C write to SI Unit Prefixes

Homework Statement I am trying to plot a graph of stopping voltage against frequency The given equation is eV0 = hf - w0 So i need to change it to the form of y = mx + C in order to plot this graph V0 = h*f/e - w0/e V0 = h/e * f - w0/e -- > V0 = y , m(gradient) = h/e , x= f and -w0/e = C (y...

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...

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

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 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.

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?

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?

Why ampere is not a S.I unit?

1 Mol = SI Unit - What the...!? This is ridiculous. How can 1 Mol be considered an SI-BASE-UNIT although it is simply a factor 1 Mol = 6.022 * 10²³ Every attempt to explain this thorough misconception is naturally predestined to fail! I'm not looking for an explanation, neither going to...

Why is the SI unit for acceleration \frac{m}{s^2}(meters per second squared) when it is actually \frac{m}{\frac{s}{s}} (meters per second per second). Isn't the part concerning the seconds different? Wouldn't this give you different answers sometimes, or does that usually never get in the way.

Homework Statement Ok, this isn't hard, I'm just thrown off by the question. From the book: "The quantity called mass density is mass per unit volume of a substance. Express the following in SI units:" a. Aluminum, 2.7*10^-3 kg/cm^3 b. Alcohol, .81g/cm^3 Homework Equations...

I am doing my homework and i come across a question. What is the SI unit for refractive index?All my revision books did not have the answer.Or perhaps the book is wrong by any chance?

This is the SI unit for luminous intensity. The definition relates to blackbody radiation emitted at a certain temperature for a certain material (so I guess it ISN'T blackbody!), platinum, I think. Except... I don't understand the necessity for the introduction of this unit. Isn't...

Hello, What is the definition for Newton

Apparently it has been decided that the new unit for beauty will be the milliHelen. One milliHelen is said to be the beauty required to launch one ship. Tee Hee