Both are short parallel lines drawn across a wire. The difference is whether the lines are the same length, which is easy to overlook at small scale.
Equal-length lines mean a capacitor. Alternating long and short lines mean a battery, with the long line positive. If the second line is curved rather than straight it is a polarised capacitor — still a capacitor, but one that must be fitted the right way round.
A single long-short pair of the battery symbol closely resembles the capacitor's two plates; the capacitor's lines are equal in length.
Drawn from the visual attributes recorded for each symbol. Only traits the two records disagree about are listed.
| Trait | Capacitor symbol | Battery symbol |
|---|---|---|
| Symmetry | bilateral | none |
| Capacitor symbol | Battery symbol | |
|---|---|---|
| What it does | Stores charge briefly and releases it | Supplies current from stored chemical energy |
| How to tell them apart | Two lines of equal length | Alternating long and short lines |
| Reading polarity | Only if polarised — shown by a curved plate or a plus | Always — the longer line is positive |
| Why they look alike | Both draw conductors as parallel lines across the wire | A single long-short pair is nearly the capacitor's shape |
| Relationship (from Symbolwise's records) | Commonly confused with Battery symbol — A single long-short pair of the battery symbol closely resembles the capacitor's two plates; the capacitor's lines are equal in length. | Commonly confused with Capacitor symbol — A single long-short pair closely resembles a capacitor's two plates; the difference is that the capacitor's lines are equal in length. |
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the component is, how its symbol is conventionally drawn, and where the ANSI and IEC conventions differ. Not used for any claim about the text of IEC 60617, which is paywalled and was not consulted.
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the component is, how its symbol is conventionally drawn, and where the ANSI and IEC conventions differ. Not used for any claim about the text of IEC 60617, which is paywalled and was not consulted.
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the component is, how its symbol is conventionally drawn, and where the ANSI and IEC conventions differ. Not used for any claim about the text of IEC 60617, which is paywalled and was not consulted.
Alpha is a Greek letter and stands for a quantity — an angle, a coefficient, a significance level. The proportionality sign is an operator and stands between two quantities to say they keep a constant ratio. The drawings differ in that the proportionality sign's right-hand stroke runs out in an open curve rather than closing into the letter's tail.
Look at the left-hand edge. A straight flat back is an AND gate: the output is true only when every input is. A curved concave back is an OR gate: true when any input is. Everything else about the shapes is similar, which is why the back edge is worth checking deliberately rather than at a glance.
Look at the pattern. Even short dashes throughout is a hidden line: an edge that exists but is concealed behind material. Long dashes alternating with dots is a centre line: an axis of symmetry or the centre of a circle, which is not a physical edge at all. Reading a centre line as an edge is the commonest beginner's error on a drawing.
The contactless indicator is four nested arcs and marks a payment card or terminal. The N-Mark is a wave-like capital N, is a trademark of the NFC Forum, and marks where to tap a device for near-field communication generally. The underlying radio technology overlaps, which is why the two get used interchangeably even though the marks belong to different bodies.