Chapter 3: Electricity: Circuits and their Components
We use electricity everywhere. In this chapter we open a torch to meet cells, batteries, lamps and LEDs, build complete circuits and a switch of our own, draw circuits with standard symbols, and test which materials let current flow, always staying safe.
In this chapter you will
- identify the parts of a torch and a cell's terminals
- build circuits with lamps, LEDs and switches
- draw and read circuit diagrams
- sort conductors and insulators and use electricity safely
Topics
- A Torchlight: Cells and Batteries NCERT 3.1–3.2.2
A cell has a + terminal (cap) and a − terminal (disc); it is a portable energy source.
- Lamps, Circuits and Switches NCERT 3.2.3–3.2.6
A lamp glows only in a complete circuit; current flows from + to −.
- Circuit Diagrams NCERT 3.3
A circuit diagram shows a circuit with standard symbols.
- Electrical Conductors and Insulators NCERT 3.4
Conductors (metals) let current flow; insulators (plastic, rubber, wood, glass) do not.
Key words
- Electric cell
- a portable source of electrical energy with + and − terminals
- Battery
- two or more cells joined + to −
- Filament
- the thin wire that glows in an incandescent lamp
- LED
- a lamp without a filament that lets current through one way only
- Circuit
- a complete path for electric current
- Switch
- a device that opens or closes a circuit
- Conductor / insulator
- a material that lets current flow easily / does not
Summary
- A cell has + and − terminals; cells joined + to − make a battery.
- A lamp glows only in a complete circuit; an LED works one way only; a switch opens or closes the circuit.
- Circuit diagrams use standard symbols.
- Metals conduct electricity; plastic, rubber, wood and glass are insulators.