An electron moves along $+x$ direction. It enters into a region of uniform magnetic field $\overset{\rightarrow}{B}$ directed along $-z$ direction as shown in fig. Draw the shape of trajectory followed by the electron after entering the field. OR A square-shaped current-carrying loop MNOP is placed near a straight, long current-carrying wire $A B$ as shown in the fig. The wire and the loop lie in the same plane. If the loop experiences a net force $F$ towards the wire, find the magnitude of the force on the side '$\mathrm{NO}$' of the loop.