WORKSHEET #6 2/30/2012 1. Two point charges, with charges q1 and q2, are each moving with speed v toward the origin. At the instant shown q1 is at position (0, d) and q2 is at ( d, 0). (Note that the signs of the charges are not given because they are not needed to determine the magnitude of the forces between the charges.) (a) Compute the magnitude and direction of the electric force on q2 due to q1. (b) Compute the magnitude and direction of the magnetic force on q2 due to q1. (c) Compute the magnitude and direction of the electric force on q1 due to q2. (d) Compute the magnitude and direction of the magnetic force on q1 due to q2. (e) Do the electric and magnetic forces obey Newtonʼs Third Law? 2. A current bit of length dl pointing in the positive ydirection is carrying a current of magnitude I. Find the magnetic field (note that the answer should be a vector) at the point P shown in the figure due to this current bit. 3. Four very long, current-carrying wires in the same plane intersect to form a square with side lengths of 48.0 cm, as shown in the figure . The currents running through the wires are 8.0 A, 20.0 A, 10.0 A, and I. Find the magnitude and the direction of the current I that will make the magnetic field at the center of the square equal to zero. You can assume that the magnetic field due to a very wire carrying a current I is given by μ0I/ (2πr) at a distance r from the wire and that the direction of the magnetic field is given by the right hand rule. 4. A square loop of wire with side length a carries a current I1. The center of the loop is located a distance d from an infinite wire carrying a current I2. The infinite wire and loop are in the same plane; two sides of the square loop are parallel to the wire and two are perpendicular as shown. What is the magnitude and direction, F, of the net force on the loop? 5. Use Ampereʼs law to find the magnitude and direction of the magnetic field at a distance r from the center of a long wire that has radius a and carries a uniform current per unit area j in the positive direction. Obtain the magnetic field outside the wire (r>a) and inside the wire (r