Posted by
**Devon** on
.

(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.