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Lesson 19
(1) An infinitely long wire on the y-axis carries a 20A
current in the +y-direction. At the point (1,0,0)
where coordinates are in meters, find
1. the direction of the magnetic field
2. the magnitude of the magnetic field
(2) How large is the contribution from the part of the
wire between the points (0,-1,0) and (0,2,0)?
(3) A long straight wire is attached to a circular loop
of radius 2.0m as shown. A 15.0A current runs
upward along the straight wire. What must be the
direction and magnitude of the current in the loop so
that the magnetic field is zero at the center of the
loop?
(4) Find the magnetic field at the center of an
equilateral triangle wire frame carrying current I.
(5) Two infinitely long wires carry equal currents of
8.0A running anti-parallel to each other. They are
both parallel to the z-axis, and are located on the xaxis at x=3.0m and x=0.0m respectively. Find the
magnetic field at the following points on the x-y
plane:
(a) (5,0,0)
(b) (1,0,0)
(c) (3,1,0)
(6) What is the direction of the magnetic field at the
point A due to the currents on two infinitely long
wires as shown?
(7) Two parallel 10cm long wire a distance 0.8mm
apart carrying anti-parallel current of the same
magnitude I repel each other with a force of 0.4mN.
What is the value of I?
(8) A rectangular wire frame is placed near an
infinitely long wire. Both carry currents. Find
1.
2.
3.
4.
the force on ab
the force on cd
the sum of forces on bc and da
the net force on the frame