Answer
a) The fields should be uniform and equal in magnitude. However, their direction has to be in opposite direction. The lower field should point into the paper and the upper field should point out of the paper.
b) The emerging kinetic energy is the same as the initial kinetic energy. Since the magnetic force is perpendicular to velocity, it change only the direction of velocity, and not its magnitude. Thus, kinetic energy does not change.
Work Step by Step
a) The fields should be uniform and equal in magnitude. However, their direction has to be in opposite direction. The lower field should point into the paper and the upper field should point out of the paper.
b) The emerging kinetic energy is the same as the initial kinetic energy. Since the magnetic force is perpendicular to velocity, it change only the direction of velocity, and not its magnitude. Thus, kinetic energy does not change.