Which component is primarily affected by polarity in a circuit?

The diode is primarily affected by polarity in a circuit because it is a semiconductor device that allows current to flow in one direction only. The operation of a diode is inherently dependent on the applied voltage's polarity: when the anode is connected to a higher voltage relative to the cathode, the diode becomes forward-biased and conducts current. Conversely, if the cathode is at a higher voltage than the anode, the diode becomes reverse-biased, and current does not flow through it.

In contrast, resistors do not have polarity; they allow current to flow regardless of the direction. Capacitors store electrical energy and have polarity when they are electrolytic, but they can still function in AC circuits where the polarity alternates. Inductors also do not depend on polarity since they oppose changes in current flow, but they store energy in a magnetic field, which is not directionally dependent like it is in diodes. Thus, the unique ability of diodes to control the direction of current flow based specifically on polarity distinguishes them in this context.