Energy and light

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