4 (15 points). The four conductors at the four corners of a square of side 2.50 cm and they each carry a current of the same magnitude, I= 3.10 A as shown in the figure. What are the magnitude and direction of the net magnetic field produced by those four conductors at the center of the square? 5a (6 points). Referring to the loops of conductors shown in the figure, what is the direction of the current induced coil 2 : (a) if the current in the coil 1 increases? (b) if the current in coil 2 decreases ? (c) if the coil in the coil 1 is constant ? Coil 1 Coil 2 5b (14 points). A lightning bolt produces a rapidly varying magnetic field . If the bolt strikes the earth vertically and acts like a current in a long straight wire, it will induce a voltage in a loop aligned like in the figure. What voltage is produced in a 0.500 m diameter loop 75.0 m from a 3.00x10* A lighning strike if the current falls to zero in Wire Coll 35.00 us ? What it the direction of induced current in the coil? 6 (15 pts.). Consider the arrangement shown in the figure. Assume R =10.0 02, 1 = 1.35 m, and a uniform magnetic field of 2.30 T is directed into the page. At what speed should the bar be moved to produce a current of 0.750 A in the resistor. Find the direction of current in the loop and the magnetic force acting on the conductor