We claim that the changing fields are also the sources of the fields - changing B makes E, changing E makes B, and the wave continues to recreate itself. Lets convince ourselves that the transverse wave is consistent with the time dependent fluxes required by Faraday’s and Maxwell’s laws for induced fields: Consider the two test loops shown below for applying Faraday’s law. The loops are in the plane perpendicular to the magnetic field (the B field is in/out of the page), with two sides parallel to the E field (up/down,) and the other 2 parallel to the direction of the wave velocity (left/right.) For loop 1, E · ds = 0. Why is that? The flux itself (ΦB) is obviously NOT zero; why do I say that? The other side of Faraday’s law (dΦB/dt) implies that since the EMF is zero, the rate of change of total flux is also therefore zero. Looking at the change in net flux, explain why dΦB/dt = 0 for this loop. (Hint: this is a wave; what do the fields like a moment later?) Loop 2 has non-zero R E · d and non-zero dΦB/dt, even though Φ = 0. Justify these claims for loop 2.
We claim that the changing fields are also the sources of the fields - changing B makes E, changing E makes B, and the wave continues to recreate itself. Lets convince ourselves that the transverse wave is consistent with the time dependent fluxes required by Faraday’s and Maxwell’s laws for induced fields: Consider the two test loops shown below for applying Faraday’s law. The loops are in the plane perpendicular to the magnetic field (the B field is in/out of the page), with two sides parallel to the E field (up/down,) and the other 2 parallel to the direction of the wave velocity (left/right.)
For loop 1, E · ds = 0. Why is that?
The flux itself (ΦB) is obviously NOT zero; why do I say that? The other side of Faraday’s law (dΦB/dt) implies that since the EMF is zero, the rate of change of total flux is also therefore zero. Looking at the change in net flux, explain why dΦB/dt = 0 for this loop. (Hint: this is a wave; what do the fields like a moment later?) Loop 2 has non-zero R E · d and non-zero dΦB/dt, even though Φ = 0. Justify these claims for loop 2.
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