What could cause a capacitor to leak current?

A capacitor can leak current due to the effects of both high temperature and excessive voltage.

High temperatures can accelerate the degradation of the dielectric material within the capacitor, leading to increased leakage current. Elevated temperatures can affect the molecular structure of the dielectric, causing it to become less effective at insulating and ultimately leading to current flow that would not occur under normal conditions.

Excessive voltage, on the other hand, can exceed the dielectric breakdown voltage of the capacitor. When the voltage across the capacitor surpasses its rated value, it can create a conduction path through the dielectric material. This breakdown can lead to increased leakage as well, and may sometimes result in permanent damage to the capacitor.

Therefore, it is accurate to say that both high temperature and excessive voltage can contribute to the phenomenon of current leakage in a capacitor, making the choice that includes both factors correct.