Part A How large a current would a very long, straight wire have to carry so tha
ID: 1323147 • Letter: P
Question
Part A
How large a current would a very long, straight wire have to carry so that the magnetic field 2.20cm from the wire is equal to 1.00 G (comparable to the earth's northward-pointing magnetic field)?
I= _______________ A
Part B
If the wire is horizontal with the current running from east to west, at what locations would the magnetic field of the wire point in the same direction as the horizontal component of the earth's magnetic field?
o at all points directly south of the wire
o at all points directly north of the wire
o at all points directly above the wire
o at all points directly below the wire
Part C
Repeat part (b) except the wire is vertical with the current going upward.
o at all points directly south of the wire
o at all points directly north of the wire
o at all points directly above the wire
o at all points directly below the wire
Explanation / Answer
circuital Ampere's law states:
J = Integral over a closed path ( vector-B . vector-dr ) = M0. I
Where vector-dr is the infinitesimal displacement along the closed path
M0 = magnetic permeability of the vacuum
I = total current enclosed by the path
If we choose a circular path of radius 2.2x10?