- #1
DoobleD
- 259
- 20
I wonder if it is possible to generate a propagating EM wave by making a single charge oscillate in vacuum ?
In practice, when we create EM waves, we (always ?) have opposite charges oscillating, like with a dipole antenna :
In the dipole antenna case, I can see how the fields detach from the antenna when opposite charge oscillate. But if we only have a single charge oscillating in vaccum, is it still possible for the fields to "detach" from the charge ?
When the single charge oscillates, I can picture in my head the E field progressively updating, like waves on ropes (the rope being the E field here). That sounds kind of like an EM wave. But it seems a totally different situation than with a dipole antenna. Here it doesn't seem like the field can "detach" from the charge. Also, I'm not sure the magnitude of the field really varies in space and time here, it seems more like only its direction changes.
I didn't try to calculate anything, not sure where to start for this question. So I'm just trying to picture things in my head, and I realized I don't know how to interpret the field around a single charge oscillating in vaccum. Is it a an wave, is it not really ?
In practice, when we create EM waves, we (always ?) have opposite charges oscillating, like with a dipole antenna :
In the dipole antenna case, I can see how the fields detach from the antenna when opposite charge oscillate. But if we only have a single charge oscillating in vaccum, is it still possible for the fields to "detach" from the charge ?
When the single charge oscillates, I can picture in my head the E field progressively updating, like waves on ropes (the rope being the E field here). That sounds kind of like an EM wave. But it seems a totally different situation than with a dipole antenna. Here it doesn't seem like the field can "detach" from the charge. Also, I'm not sure the magnitude of the field really varies in space and time here, it seems more like only its direction changes.
I didn't try to calculate anything, not sure where to start for this question. So I'm just trying to picture things in my head, and I realized I don't know how to interpret the field around a single charge oscillating in vaccum. Is it a an wave, is it not really ?