15. A rectangular coil with resistance R has N turns, each of length & and width w as shown in the following figure. The coil moves into a uniform magnetic field B with constant velocity v. What are the magnitude and direction of the total magnetic force on the coil (i) as it enters the magnetic field, (ii) as it moves within the field, and (iii) as it leaves the field? A X X X X X X X X X X X X X X W X X X X X X X X X X X X X X X X X X X X X