Electricity: Circuits and their Components
1. Uses of Electricity
Electricity powers
1. cooking (e.g., microwave),
2.lighting (e.g., bulbs),
3.transportation (e.g., trains),
4. heating/cooling (e.g., AC),
5.entertainment (e.g., TV),
6.communication (e.g., phone),
7. and others (e.g., computer).
Grouping: By location (home, school), function (daily needs, fun), or device type (portable, fixed).
2. Torchlight and Its Components
- A torchlight uses batteries to produce light via a lamp and switch.
Components:
- Electric Cell: Portable power source with positive (+) and negative (-) terminals.
- Battery: 2+ cells connected (+ to -) for more power.
- Incandescent Lamp: Has a filament that glows when heated.
- LED Lamp: No filament; glows when current flows correctly (longer wire = positive, shorter = negative).
- Switch: Completes or breaks the circuit to turn the lamp on/off.
3. Electrical Circuit
- A complete path for electric current to flow from the positive to negative terminal of a cell through a device (e.g., lamp).
- Current flows only in a closed circuit. An open circuit (e.g., switch off) stops the flow.
- Direction: Current flows from positive to negative.
4. Circuit Diagrams
- Use symbols to represent components (e.g., cell, lamp, switch, wire).
- Makes circuits easy to draw and understand.
- Key symbols: Cell (long line = +, short = -), LED (triangle with arrows), switch (line or gap).
5. Conductors and Insulators
- Conductors: Allow current to flow (e.g., metals like copper, aluminium).
- Insulators: Do not allow current to flow (e.g., plastic, rubber, wood).
- Wires are made of conductors (e.g., copper) and covered with insulators (e.g., plastic) for safety.
- Safety: Our body conducts electricity. Avoid wet hands or damaged devices to prevent shocks.
6. Key Points
- Cells and batteries power devices portably.
- Lamps (incandescent/LED) glow when current flows correctly.
- Switches control circuits (ON = closed, OFF = open).
- Conductors (metals) and insulators (plastic) are essential for safe circuits.
- Direct Current (DC): From batteries for small devices.
- Alternating Current (AC): From wall sockets for large appliances.
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