Question

4. Shown at right is a cross-sectional view of two long, straight wires at are parallel to each other, placed near point P. One wire carries a current i, into the page; the other wire is twice as far away from P and carries a current 2i, out of the page. 2i (Hint: The magnetic field from a current-carrying wire is proportional to the current through the wire and inversely proportional to the distance away from the wire.) Draw and label a vector on the diagram to show the direction of the net magnetic field at point P. If the magnetic field is zero at point P, state so explicitly. Explain your reasoning a. O- out of the page &-into the page b. Suppose that a third wire, carrying another current i, out of the page, passes through point P Draw a vector on the diagram to indicate the magnetic force, if any, exerted on the current in the new wire at P. If the magnitude of the force is zero, state so explicity New wire at point P third wire is placed the the magnetic field at point P is zero. Determine the location of the third wire. Clearly indicate on the diagram at right the correct location of the new wire. Explain how you determined your answer. Use the back of this page if necessary OTutorials in Introductory Physics, Physics Education Group, Department of Physics University of Washington (Summer 2018, Mazur version)

Answer 1