Every circuit component — cell, switch, bulb, resistor, meter — has a standard symbol, so a circuit diagram means the same thing to everyone who reads it.
Standard symbols used to draw circuit diagrams — NCERT Table 11.1.
An electric circuit is made up of a cell (or battery), a plug key, connecting wires, and one or more electrical components. Rather than drawing realistic pictures of each part, it's far more convenient to draw a schematic circuit diagram, where each component is replaced by a simple, universally recognised symbol.
A cell is drawn as one long thin line (positive terminal) next to one short thick line (negative terminal); a battery is just several cells in a row. A plug key or switch is drawn as a gap in the wire with a small lever — open when the lever is lifted, closed when it completes the connection.
A resistor is drawn as a zigzag line, and a rheostat (variable resistance) is the same zigzag with an arrow through it. An ammeter and voltmeter are both drawn as circles, labelled 'A' and 'V' respectively. Wires that simply touch and connect are shown with a solid dot at the junction; wires that cross *without* connecting are drawn as one hopping over the other with no dot.
Learning these symbols means anyone — student, electrician, engineer — can read the same circuit diagram and understand exactly how the components are connected, without needing a single word of explanation.
Key exam points
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Circuit diagram class 10 | Define circuit diagram | Circuit diagram with ammeter and voltmeter · Darshan classes