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I'm trying to
find distribution of magnetic field from solenoidal coil, but
I don't know, where I have a mistake :( I've done it with femm, but I have to find also an analytical solution of my problem. I'm starting from potential: 2Pi z2 r2 / / / V=(I/4Pi)* | | | (1/R) rdr dz dfi / / / 0 z1 r1 z1, z2 - start and end of coil (long), r1, r2 - inner and outer radius of solenoid, R - distance of P point from dV element of coil. P(x,0,z) - P is on y=0 plane, due to cylindrical symmetry. Coordinates of dV element of solenoid are Q(rcos(fi), rsin (fi), b) Then, distance R = Square Root {r^2+x^2-2rxcos(fi)+(b-z)^2}. And now I have to calculate components of magnetic field in x and z axis. And I don't know how to do it :( From my point z component of field is Hz=-dV/dz. It's simple to calculate dV/dz (d(1/R)/dz), and I solve an integrate 2Pi z2 r2 / / / H=(I/4Pi)* | | | ((b-z)/R^3) rdr db dfi / / / 0 z1 r1 b- coordinate of dV on z axis , (I want to distinct b from P point coordinates (x,0,z). But calculations says, that I'm wrong. Where is an error ????? And how to calculate x component of field ??? Hx=dV/dx ??? Maybe something with fi angle (cos fi ???) I need your help !!! Michał |