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A zigzag or a plain rectangle in a circuit, marking a resistor.
Also known as: Zigzag symbol, Resistance symbol, Resistor schematic symbol, Zig-zag resistor, Resistor rectangle
A resistor is drawn as a zigzag in North American schematics and as a plain rectangle under IEC practice. Both are current, which is why the same component looks like two different things depending on where the diagram was drawn.
Marks a resistor in a circuit diagram: a component that opposes the flow of current and drops voltage across itself.
Contexts: Electrical equipment
Is drawn two incompatible ways that are both in current use — a pointed zigzag in North American practice, and a plain unfilled rectangle under IEC practice followed across most of Europe.
Neither is a variant of the other. A reader cannot tell which convention a schematic follows from the symbol alone, only from the diagram's origin or its other symbols.
Contexts: Electrical equipment
In its IEC rectangle form is easily misread as a fuse or an unlabelled functional block, both of which are also plain rectangles distinguished only by additional marks.
Contexts: Electrical equipment
Is drawn two different ways by two different standards. The international form defined by the IEC is a plain rectangle with a lead at each end; the form defined by the American ANSI and IEEE standards is a series of sharp zig-zags, conventionally four peaks. Neither is a mistake and neither is old-fashioned — a reader meeting an unfamiliar drawing of a familiar component is usually looking at the other continent's standard rather than at an error.
Contexts: Technical drawing, Electrical equipment
Carries its value beside the symbol, not inside it. A schematic gives the resistance as a number with a unit — 4k7, 220R, 1M — and often a tolerance and power rating too, because the drawing shows what the component is and the annotation shows which one to buy.
Contexts: Technical drawing, Electrical equipment
Related forms that are not treated as separate canonical symbols — see our variant rules.
IEC rectangle form
A plain unfilled rectangle, the international form, used in European, British and most modern educational schematics.
ANSI zig-zag form
The sawtooth line familiar from American textbooks and hobbyist schematics, defined by the ANSI and IEEE graphic symbol standards.
Variable resistor
The same body crossed by a diagonal arrow, marking a resistance the user or the circuit can change. With a third connection taken from a wiper it becomes a potentiometer instead.
Either a sharply pointed zigzag line of three or four peaks set into a straight wire, or a plain empty rectangle with the wire entering each short end.
The IEC rectangle form of the resistor and the fuse symbol are both plain rectangles in a wire, separated only by the fuse's additional line.