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Calculating how magnetic field strength decreases with distance
Hi everyone, I am trying to calculate the decrease in magnetic field strength over distance, using a formula I found on this thread http://www.physicsforums.com/showthread.php?t=522223 The formula...
View ArticleElectric potential
There are two sphere of radius a and b and they are connected by conducting wire. Then why the electric potential becomes same of both the sphere?
View ArticleQuestion about cylindrical Coordinates
I'm confused why when using cylindrical coordinates three unit vectors are needed. My book says that the three unit vectors are one for the radial direction which is bound to the xy plane and then a...
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How cross-section area of single E-M wave looks like?
This question has been asked probably many times, and is inspired by area that appears in denominator of energy flux unit [W/m^2]. From what i have read so far, i come to conclusion, that this post...
View ArticleTwo isolated metal cubes: Negative ΔS? Thermodynamics
Hi. So let's say you have two identical cubes with expansion coefficients of approx. zero. These cubes are thermally in contact with each other, and otherwise isolated from the surroundings. One cube...
View ArticleRelationship between gravitational field strength and potential
Hi, I am a bit confused with the relationship between gravitational field strength and gravitational potential. As far as I know, gravitational field strength is defined as:...
View ArticleSteady-state incompressible Navier-Stokes discretization
Hi, I would like to solve the steady-state incompressible Navier-Stokes equations by a spectral method. When I saw the classic primitive-variable finite element discretization of the time-dependent...
View ArticleExergy and Gibbs free energy
Hi. I have two questions: 1) Is -ΔG the amount of useful work a system can do while the pressure and temperature of the surroundings are constant? 2) Is exergy = -ΔG only if the pressure and...
View ArticleEmission and Reflection
Dear Forum, An object, like a metal, that is highly reflecting (white body) is very different from a very emissive object (black body). An object that closely behaves like a black body absorbs all the...
View ArticleIntensity of natural light after polarization
I read that if a beam of unpolarized light goes through a polarizer, the intensity of the polarized beam is equal to half the intensity of the original beam. Can someone explain me why? I thought the...
View Articlephotoactivated localization microscopy (PALM)
I have been reading up on PALM works and am still confused about a few things. In particular, (1) how can you only excite a few molecules at a time and then only photobleach those molecules? Won't...
View ArticleConfusion of the electrical conductivity unit in CGS.
Hello. Electrical conductivity is written as [itex]\frac{n_{e}e^{2}}{m_{e}\nu_{ei}}[/itex] where [itex]n_{e}, e, m_{e}[/itex] and [itex]\nu_{ei}[/itex] are for electron density, charge, mass and...
View ArticleForce accelerates center of mass same regardless of where applied?
Is it true that the center of mass of an object will be accelerated with the same direction and magnitude from the same force no matter if the force is applied to the center of the object or to the...
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Traveling electric and magnetic fields
Hi this is my first thread since joining the website, so let me know if I am violating any rules here. I read a bunch of rules to follow in the website but don't think I can remember everything. I am...
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what's the direction of induced emf here?
This thing has confused me for long .I have not come across any satisfactory answers on my own or while browsing through the internet. Everybody has seen the example of a rod moving while on parallel...
View ArticleConfusion regarding Kelvin-Plank statement of Second Law
Hello there. New here. I have read and tried to understand the Kelvin Plank statement of the second law. Essentially, it would imply, it is impossible to convert a given quantity of heat completely to...
View Articlea point between 2 magnets, what remains constant at that point?
a fixed spacial point between 2 fixed magnets. if I place different blocks of material on that point, is the H that will remain the same? or is it the B? or just the MMF (magnetic motive force), while...
View ArticleQuestion about the possible use of waves in a certain device
So I'm a diabetic and i know about the prickles meters, i want to know how they work though. I would assume it has to do with some form of EM wave possibly reflecting off just the glucose molecules in...
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General equation of motion with gravitational field
I was studying the equations of free fall and of launch when I realize that those equations are spetial case of a object in motion through of a gravitational field. So exist some general equation that...
View ArticleTension in the thread: Centripetal Force in the Vertical plane
I get the theory: Fc = Ft + Fg Uniform circular motion, in the vertical plane. Fc = net force = centripetal force Ft = force of tension in the string Fg = force of gravity so at the top, with vector...
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