New Gaussian surfaces?
I invented this problem you don't have to do it... take 2 wrinkled spheres of opposite charge rhocharge2 and equal radius, volumerho1 of the spheres=[tex]1+\frac{1}{2}sin(m\pi) sin(n\phi), m=6,...
View ArticleScattering field formulation used in DG-FEM
Hello! Reading up on simulations of electromagnetic scattering with DG-FEM and trying some myself, I got stuck. In some of papers I have read, a scattering field formulation is used, in which the total...
View Articleeddy currents
hi all. I understand wikipaedias explination of eddy currents but could someone please explain more fundamentaly how they work. Thanks in advance :)
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Inverted Pendulum on Cart: What is this term in the KE?
I am working through an example of an inverted pendulum on a cart, exactly like this: L is the length of the massless pendulum arm. Two degrees of freedom, x and theta. If I write out the kinetic...
View ArticleConfused about electromagnet??
How do i calculate the magnet field for an Solenoid with an ironcore with x windings and y amps.. The same for an horseshoe magnet, where there is an air gap about 2mm.. For some reason does my...
View ArticleIdeal gases and partial volume
What does it mean by 21% oxygen and 79% nitrogen by volume? Because won't the oxygen and nitrogen have the same volume which is the volume of the whole container? nTRT/VT=nO2RT/VT+nN2RT/VT so why would...
View ArticleHome made solenoid
I wound 4 layers on a piece of 3/4 conduit. The wire is 20 gauge (.032) and the coil length is 7 inches. I put 5 amperes into the coil and a bolt that fits the conduit didn't move. It stuck to one side...
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problem with use of 'velocity' of charged particle in lorentz force eq
if we assume a charge particle enters in a uniform magnetic field with velocity V w.r.t inertial frame as shown fig. then according to the situation shown there will be force acting on particle due to...
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Steady State Angle of a Pendulum with Wind
I'm having trouble solving this problem. I'm trying to find the steady state angle of a rod with wind /fluid drag. Assume Cd, L, U, etc. are known. The viscous and form drag forces are a function of...
View Articleconfused about the electric field at the surface of a conductor
Hi We know that the electric field at the surface of a conductor only have a normal component equal to ρ /ε (finite number). But lets consider the point P (at the surface of a conductor ) . Assume...
View ArticleAverage kinetic energy of molecules
Hello, The formula for average kinetic energy of molecule is: k=3/2KT. Can anyone please explain the derivation without using calculus? Thanks, -- Shounak
View ArticleDependence of deceleration of a moving body with the medium's density
Is there a relation between the deceleration experienced by a body in motion to the density of the medium? Stokes' law of viscosity is there for fluids. But how would one calculate the drag on a moving...
View Articletrifilar suspension/pendulum
trifilar suspension/pendulum is used to determine the moment of inertia(MOI) of an irregular body. In order to determine MOI, we need to place the given body whose c.g. has to pass through the c.g. of...
View ArticleImportance of Ampere's Law
Consider a hollow cylinder carrying a current I and a wire outside the cylinder carrying a current I'. Let's say the cylinder is symmetrical with even current distribution etc.. so the B field at any...
View Article∇E = 0 in an Ohmic, 2d Hall conductor with constant B?
I've been trying to figure this out for long now but unfortunally, I'm not able to prove that ∇E = 0 in an Ohmic, 2d Hall conductor E = Rj + v×B with B = const (and orthogonal to j). There is quite a...
View ArticleGenerality of the Euler Lagrange equations
Hi I wanted to know for which cases the Euler Lagrange equations are applicable? 1.) Imagine that we have a kinetic Energie T(q,q') and a potential that also depends on velocity V(q,q'). As far as i...
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Statics, centroids of lines, areas and volumes
Hi to everybody. I´m reading a book about statics and I cannot understand this chapter. I have been calculating moments of forces in hundreds of problems, when I found a force acting on a body I needed...
View Articleeinstein summation notation for magnetic dipole field
I can do this derivation the old fashioned way, but am having trouble doing it with einstein summation notation. Since [itex]\vec{B}=\nabla \times \vec{a}[/itex] [itex]\vec{B}=\mu_{0}/4\pi (\nabla...
View ArticleNewton's third law and energy transfer
If newtons third law says there is an equal and opposite reaction how can there be energy transfer. For example if I push a box and give it 1000 joules of energy wouldn't it "give back" the energy....
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Optics Problem
Does anyone know how to solve this problem? I tried using the spherical interface formula (n1/p)+(n2/q)=((n2-n2)/R) and I get q=15cm which I cannot seem to relate to the answer provided (23cm). Anyone...
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