From my understanding, the frequency and wavelength of a mechanical wave can be observed by the motion of the particles (i.e., as the particles oscillate from their state of equilibrium, the wave propagates through the medium). But, with electromagnetic waves, how do we measure its frequency and ...

Hamilton's equation can be written in terms of Poisson brackets, as follows: $$\dot{q} = \{q,H\}$$ $$\dot{p} = \{p,H\}$$ where $H$ is the Hamiltonian of the system. Now, wikipedia says that the solution of these equations can be written as: $$q(t) = \exp(-t\{H,\cdot\})q(0)$$ $$p(t) = \exp(-t\{H,\...

I was wondering why we need the electromagnetic field tensor $F_{\mu\nu}$ to be a tensor and why can't we work with the electric and magnetic fields while dealing with the electromagnetic field Lagrangian density for flat spacetime. I kind of get the intuition behind it, because you cannot write ...

Thought experiment: A block with a mass of 10kg is moving right with velocity 1m/s. I pushed the object leftwards so that its velocity changed to -1m/s. In this case, the kinetic energy of the block remains constant(5J) before and after the push. Does this mean that no work is done on the block? ...