Quick questions on Electromagnetism and motors - TCE Physics (Tasmania)

When a straight conductor of length $L$ carrying current $I$ sits in a uniform magnetic field of strength $B$, it experiences a force:

A single charge $q$ moving at speed $v$ through a field $B$ feels:

A rectangular coil of $N$ turns and area $A$ carrying current $I$ in a field $B$ experiences a torque:

A direct current motor converts electrical energy into rotational kinetic energy using the motor effect. A current-carrying coil sits in a magnetic field, and the opposing forces on its two sides produce a torque. The key engineering problem is that as the coil passes through the vertical position the torque would reverse and stop the rotation. A split-ring commutator solves this by reversing the current direction in the coil every half turn, so the torque always acts to keep the coil rotating the same way.