posted by Devon .
(the drawing is of a square with each side equaling L and the opposites of each corner are equal to each other, so the mystery corner would be 3I)
Four parallel long straight wires are carrying current
perpendicular to the page, and the points at which they pass
through the page correspond to the corners of a square of side L.
As shown in the diagram two of the wires carry currents of 2I into
the page, while one of the other wires carries a current of 3I out of
the page. The fourth wire carries an unknown current.
(a) If the net force per unit length on the wire with the
current of 3I is zero, what is the magnitude and direction of the current in the fourth wire?
(b) In the space at right, draw a free-body
diagram for the wire passing through the upper left
corner of the square, showing the forces acting on that
wire from the other three wires.
(c) What is the magnitude of the net force per unit length on the wire passing through
the upper left corner of the square, due to the other three wires? Express the magnitude in terms
of variables specified above as well as =d)
Determine the magnitude and direction of the net magnetic field at the center of the
square because of the four wires. Express the magnitude in terms of variables specified above as
well as appropriate constants.
(e) If we add another wire, carrying a current I into the page, parallel to the others and
passing through the center of the square, what is the magnitude and direction of the force per unit
length that it experiences.