Recent content by USeptim

... Well, it's a personal interpretation...

Hello, Reading Richard Feynman’s book “Quantum Electrodynamics” (Edited by Advanced Book Classics), I read that the electron’s self-energy is infinite and that has been a trouble for QED during 20 years. Feynman proposed a solution based on a cut-off, but that’s not fully satisfactory and I...

The radiated electric field depends on 1/r but it's perpendicular to the direction of propagation so the total flux is zero. If you take an sphere centered on an accelerating particle the electric field will be perpendicular to the surface everywhere so the flux will be zero.

G.P.E. is so usefull because the mass of objects is so small compared to the mass of the Earth that all the energy in the gravitational interaction comes back to the object, so, when a particle returns to its original possition (let's said it the zero height), all the potential energy is...

Hi, It's obvious that the flux will decrease since the loop is shinking but I'm afraid this reduction will be compensated with the term - dx · (v/c x E) so that the magnetic field will not change. In the link given by vanhees71, https://en.wikipedia.org/wiki/Leibniz_integral_rule, v is "the...

Hi, About your first question, both forms differ only in the sign and since the reactance is a complex magnitude, the sign is not relevant. As for your second question, I don't see in https://en.wikipedia.org/wiki/Susceptance the definition of G that you have written.Sergio

Thanks mfb, I will try the two first options.Sergio

Hi, I have been some time searching information about the flux of momentum in the electromagnetic field. With the help of some members of this forum, I learned that the Maxwell stress tensor was very related with this flux since its divergence plays the same role in the continuity equation for...

Thank you DaleSpam for your answer, so the correct four vector would be the one obtained by transforming the fields. If want to transform the energy and momentum density I have to do it as a energy stress tensor, which transforms on boosts as explained in this link...

I have to rectify about what I have said, the speed will be w*d where d is the distance of any point to the axis of rotation, not to the center of the cube. Sorry for that.

Hi, Maybe this thread can help you but I'm not sure it's the same: https://www.physicsforums.com/threads/kinetic-energy-of-a-rotating-cube.546690/ Anyway, you can always integrate, the speed at any point will be w*d where d is the distance of that point to the center,Sergio

Electromagnetic field has a density of energy U = ε/2*E2+ μ/2* H2 And a density of momentum, given by the Poynting vector S = E x H For an element of volume dV you have a four vector of energy and momentum which is [E,P] = dV * [U, S] Being E the energy in the element of volume and P the...

A collision between two objects, let's name them A and B, will depend on their relative velocities, in fact it will depend on their relative speeds. This relative speed is the speed measured for B in A's inertial frame or the speed measured for A in B's intertial frame, which is the same. The...

I agree with cpsinkule, I don't see any paradox here. On the surface of an ideal conductor you will have a charge density which will cause an abrupt change in electric field so inside the charged shell you will have no field although outside there is electric field. Ideal conductors does not...

The electrons lose the same amount of energy in the resistance plus wire that the energy they get in the battery. The electrons leaving the resistance may leave the loop being replaced by other electrons, anyway electrons are indistinguishable except by their quantum numbers. With a capacitor...