- #1
doktorwho
- 181
- 6
Homework Statement
##l/l_0=100##
##S=3 (cm)^2##
##B_r=200μ_0H_c=2mT##
##R=10Ω##
No current runs through the feromagnetic core. Calculate the charge ##q## that goes through ##R## from the moment in the diagram to the moment it is removed from the core.
Homework Equations
3. The Attempt at a Solution [/B]
I just have one small lack of understanding concerning this problem.
From the ampere's law i get:
##Hl+H_0l_0=0##
and
##Hl+\frac{l_0}{μ_0}B=0##
Here the professor said that we from the diagram suppose that ##H=-H_c## and then continued to calculate ##H## to be ##H=25/\pi [A/m]##
Why did he suppose that? And what would happen if i supposed ##B## to be ##B_r##. Is there a thing that happens that tells me that my supposition was wrong and that i should do the other one? Could you explain this?