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Two parallel lines across a break in a wire, marking a capacitor.
Also known as: Cap symbol, Two parallel lines symbol, Condenser symbol
Two parallel plates with a gap between them mark a capacitor, and the drawing is literally a picture of the component: two conductors separated by an insulator. A curved second plate means the capacitor is polarised and must be fitted the right way round.
Marks a capacitor: a component that stores charge between two conductors separated by an insulator.
Contexts: Electrical equipment
Depicts the component directly — the two lines are the two plates and the gap between them is the dielectric.
Contexts: Electrical equipment
Distinguishes a polarised capacitor by drawing one plate curved, or by marking one side with a plus. Fitting a polarised capacitor backwards can destroy it, so the distinction is practical rather than decorative.
Contexts: Electrical equipment
Was called a condenser well into the twentieth century, a term that survives in automotive and older audio usage.
Contexts: Electrical equipment
Distinguishes polarised from non-polarised by the shape of the second plate. Two straight parallel lines means the capacitor may be fitted either way round; one straight line facing one curved line, or a plus sign beside one lead, means it is polarised and fitting it backwards will damage or burst it. That is the single most consequential detail in the symbol.
Contexts: Technical drawing, Electrical equipment
Related forms that are not treated as separate canonical symbols — see our variant rules.
Polarised (electrolytic) form
One straight plate and one curved plate, usually with a plus sign at the straight side. The curved plate is the negative terminal.
Variable capacitor
The plates crossed by a diagonal arrow, for a capacitance that can be tuned — the classic radio tuning capacitor.
Two short parallel lines facing each other across a small gap, each with a wire leading away from its centre; in the polarised form the far line is drawn as a shallow curve.
A single long-short pair of the battery symbol closely resembles the capacitor's two plates; the capacitor's lines are equal in length.