- #1
TerryW
Gold Member
- 191
- 13
Can anyone help me with Ex 4.1 in MTW?
What is a 'generic' field? My expectation is that it would comprise an Electric Field, with arbitrary direction, a Magnetic Field, also with arbitrary direction, and a radiation field (E and B of equal magnitude) , radiating in an arbitrary direction.
Trying to put this together however to get the Poynting density of energy flow and the density of energy is a bit of a mess however, so I suspect my expectation is wrong.
Moving on to the next bit of the problem, if you do define the unit vector n and velocity parameter α as shown, then a solution to this is a radiation field with E along the x axis, B along the y axis, producing a Poynting vector along the z axis. If you then translate to the rocket frame, E X B disappears because B becomes zero, not because B becomes parallel to E. I can't see how B ends up parallel to E.
Can anyone help?
TerryW
What is a 'generic' field? My expectation is that it would comprise an Electric Field, with arbitrary direction, a Magnetic Field, also with arbitrary direction, and a radiation field (E and B of equal magnitude) , radiating in an arbitrary direction.
Trying to put this together however to get the Poynting density of energy flow and the density of energy is a bit of a mess however, so I suspect my expectation is wrong.
Moving on to the next bit of the problem, if you do define the unit vector n and velocity parameter α as shown, then a solution to this is a radiation field with E along the x axis, B along the y axis, producing a Poynting vector along the z axis. If you then translate to the rocket frame, E X B disappears because B becomes zero, not because B becomes parallel to E. I can't see how B ends up parallel to E.
Can anyone help?
TerryW