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Leçon 8 · classe 7–9
Energy and light
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Energy is not created or destroyed — it only changes costume: chemical (fuel) → thermal → mechanical (engine). Light is an electromagnetic wave: color depends on wavelength, the rainbow splits white light into the spectrum. Light speed: 300,000 km/s — sunlight takes 8 minutes to reach us.
- ●Food energy: kilocalories — same physics as joules
- ●Redshift showed the universe expands
- ●LED saves ~90% energy vs the incandescent bulb
🌈 Fraunhofer of Munich split light into a spectrum 200 years ago — letting us learn what stars are made of without flying there.
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