Not sure I understand..
Should I get:
B = mew0*I*r / 2*pi*R2
Where r is the distance to the point in the wire we're looking for, and R is the radius of the whole wire? How does J fit into it?
The part of the question I don't get is this bit:
axis according to J = J0 r / a
The current density inside a long, solid, cylindrical wire of radius a = 10 cm is in the direction of the axis and varies linearly with the radial distance r cm from the axis according to J = J0 r / a with J0 =0.5 A/cm2 . Find the magnetic field in μT at r = 0.045 m
Ok I know from amperes law...
I have these questions on electric fields that I'm a bit confused on..
A flat circle of radius 8 cm is placed in a uniform electric field of 8.5 × 10^2 N/C. What is the electric flux (in Nm^2/C) through the circle when its face is at 51° to the field lines?
I just use EAcos(theta) don't I...