What device changes the direction of current flow through an armature?

The device that changes the direction of current flow through an armature is the commutator. This component is critical in direct current (DC) motors and generators, as it allows the electrical current to flow in one direction through the armature winding while still allowing for a continuous rotation of the rotor. The commutator periodically reverses the direction of the current as the armature rotates, ensuring that the motor continues to spin in the same direction.

Using a commutator is essential for interfacing direct current systems effectively, as it maintains the rotational motion by adjusting the polarity of the current through various segments of the winding as they pass through the magnetic field. This process ensures efficient operation and a consistent torque output.

In contrast, while capacitors, inductors, and resistors are all important components in electrical circuits, they do not serve the specific function of reversing current direction through an armature in the context of motors or generators. Capacitors store and release energy, inductors store energy in a magnetic field, and resistors limit current flow but do not change its direction. Thus, the unique function of the commutator marks it as the correct choice for this question.