What is the function of a capacitor in electrical circuits?

A capacitor serves the primary function of storing electrical energy temporarily. This stored energy can be released back into the circuit when needed, making capacitors crucial for managing power supply and maintaining voltage levels. In various applications, such as smoothing out fluctuations in power supply or providing bursts of energy during peak demands, a capacitor helps maintain the stability and efficiency of the circuit.

The ability of a capacitor to store energy is based on its construction, which typically consists of two conductive plates separated by an insulating material known as a dielectric. When a voltage is applied across the plates, an electric field is created, allowing the capacitor to hold charge. This stored energy can be significant in many electronic devices, contributing to their performance.

In the context of the other choices, increasing resistance does not describe the role of a capacitor, as capacitors actually act differently in a circuit by affecting reactive components. Similarly, a capacitor does not primarily function to decrease voltage; instead, it can even be used to stabilize voltage in some electrical applications. Lastly, while capacitors can influence current flow by charging and discharging, they do not ensure current flows in all directions; that behavior is more typical of devices like diodes, which control the direction of current flow.