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Jan30-10, 09:04 PM
P: 58
Quote Quote by GRDixon View Post
The wire induces a B field via Ampere's Law. It can be magnetostatic. The B field in a wave is induced by a time-varying E field and is not static (in time). However, when the E field between the plates of a capacitor is varied, it induces a B field much as the time-varying E field in an electromagnetic wave does. Maxwell suggested that the time-varying E field between the capacitor plates was proportional to a "Displacement Current" flowing out of one plate and into the other. These Displacement Currents theoretically induce B fields a la Ampere's Law, quite as currents of free charges do.
As elect_eng earlier said, that me observing the magnetic field due to a current will depend on my motion.. So, I could have said that the magnetic field, existing or not, will depend on the observer's state of motion..
But since, the magnetic field in an EM wave is not the same as that due to a current carrying wire, I can't say the same thing for this field.. Right??