Final answer:
A capacitor is a device used to store electrical energy, with two conductors separated by an insulator. It conserves charge and energy within an electrical system, and its storage capacity is defined by its capacitance.
Step-by-step explanation:
A device described as used to store electrical energy, typically consisting of two conductors separated by an insulator, is known as a capacitor. Capacitors have a wide range of applications, such as filtering static from radio reception or storing energy in medical devices like heart defibrillators. The two conductors, or capacitor plates, are positioned close to each other but do not touch, with the space between often filled with an insulating material called a dielectric. When connected to a battery, capacitors separate equal amounts of positive and negative charge, +Q and -Q, respectively, across the plates while remaining electrically neutral as a whole.
The amount of electrical charge a capacitor can store is called its capacitance, and conservation laws mandate that both energy and charge are conserved within an electrical system. For instance, a parallel plate capacitor showcases a direct proportionality between the electric field strength and the amount of charge it stores, affecting the voltage across the plates.