1. The problem statement, all variables and given/known data
I am trying to understand why, in an example in Griffiths E&M (3rd ed, 8.1) says that the Poynting vector of a current carrying wire that is being heated via resistance (Joule heating), has a Poynting vector pointing radially inward. The E field is parallel to the wire, B field is circumferential with the right hand rule.
2. Relevant equations
3. The attempt at a solution
I believe that the Poynting vector points in the direction of energy flow, and in the direction of the EM wave. But if the wire is radiating heat due to Joule heating, I just don't get why the Poynting vector is radially in, and not radially out. This should be so simple...
I am trying to understand why, in an example in Griffiths E&M (3rd ed, 8.1) says that the Poynting vector of a current carrying wire that is being heated via resistance (Joule heating), has a Poynting vector pointing radially inward. The E field is parallel to the wire, B field is circumferential with the right hand rule.
2. Relevant equations
3. The attempt at a solution
I believe that the Poynting vector points in the direction of energy flow, and in the direction of the EM wave. But if the wire is radiating heat due to Joule heating, I just don't get why the Poynting vector is radially in, and not radially out. This should be so simple...
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