PHYS 2002 Chapter : PHYS2002 Spring 2016 Practice Exam 2

determine the direction of the magnetic field of the current-carrying wire

A wire carries current in the plane of this paper toward the top of the page. The wire experiences a magnetic force toward the right edge of the page. Is the direction of the magnetic field causing this force (a) in the plane of the page and toward the left edge, (b) in the plane of the page and toward the bottom edge, (c) upward out of the page, (d) downward into the page?

3. Shown below(screen shot at bottom) are two wires 100cm apart,the left carrying a current of 5A out of the page and the right acurrent of 10A into the page. The point P is midway between thewires.

(a) Calculate the magnetic field at P due to the left wire,expressing your answer in terms of the unit vectors i,j,k.
(b) Calculate the magnetic field at P due to the right wire (againexpress answer in terms of i,j,k).
(c) Calculate the total magnetic field at P due to bothwires.
(d) Draw an arrow at Q, which is vertically above P, showing theapproximate direction of the total magnetic field there. (You willget full credit if arrow is in the right quadrant).
(e) The magnetic field vanishes somewhere on the line joining thetwo wires. Where does this happen: to the left of 5A wire, inbetween the two wires or to the right of the 10A wire?
(f) As a followup to (e), calculate the exact place on the linejoining the wires where the magnetic field vanishes.
(g) A long wire is placed at P, parallel to the other two wires,and carrying a current of 3A out of the page. Calculate the forceexperienced by a 1cm portion of this wire, expressing your answerin terms of the unit vectors i,j,k.