A capacitor is a device that stores a quantity of electrons. Capacitors are identified by the dielectric (insulating) material used in their manufacture.Two commonly used schematic symbols for a capacitor are shown here. Both symbols are meant to represent the two plates of a capacitor with the insulation between them. The curved plate in the lower symbol indicates that the plate should be connected to a negative polarity.
An excerpt from “Technical Institute Manual 2” from the Refrigeration Service Engineers Society online store. RSES.ORG