Concept 6 of 9Foundation
Watch on YouTubeVideoHow a bulb works
A bulb has a thin, coiled wire called the filament, usually made of tungsten. Current heats it to ~2500°C. So hot it glows white-hot, giving off light.
Tungsten is used because it has a very high melting point (3422°C) — it can glow without melting.
A broken filament = fused bulb. Throw it away, can't be fixed.
Modern LED bulbs use semiconductors instead — much more efficient.
Example
Hold a dead bulb up to light — you'll see the tiny broken wire inside.
💡 Tip:Bulbs waste most energy as heat (~90%). LEDs waste only ~20%.
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5 questions to check what you just read.
0 / 5
- Q1.The glowing part inside a bulb is the:
- Q2.Filament is made of:
- Q3.A fused bulb has:
- Q4.Filament heats up to about:
- Q5.Modern bulbs more efficient than filament: