Unformatted text preview: [ Ans. ] Φ m ( r > a ) = M zxa 5 5 r 5 , Φ m ( r < a ) = M zx 5 . (2) 9. Starting from the force equation F = ∫ J ( r ) × B ( r ) dτ, (3) and the fact that a magnetization inside a volume V bounded by a surface S is equivalent to a volume current density J m = ∇ × M and a surface current density K m = M × ˆ n , show that in the absence of macroscopic conduction currents the total magnetic force on the body can be written F = − ∫ V ( ∇ · M ) B ext dτ + ∫ S ( M · ˆ n ) B ext da, (4) where B ext is applied the magnetic ﬁeld. 1...
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This note was uploaded on 03/22/2011 for the course PHYS 425 taught by Professor Guang during the Spring '09 term at Seoul National.
- Spring '09