Black, White, Shiny
Absorbers, reflectors — and the thermos that knows all three roads
What this lesson covers
Why it matters
Wear black in June and you'll regret it by noon. Solar cookers are black inside; kettles are shiny outside; a thermos is silvered within. Surfaces have opinions about radiation.
Predict first
White clothes feel cooler in summer because white…
Dark, dull surfaces ABSORB radiation best; white, shiny ones REFLECT it. Your wardrobe is radiation engineering.
- reflects most of the Sun's radiation away — correct
- lets the heat pass through
- produces coolness
What you do
Decide for each surface: absorber or reflector — and see why each object chose its colour.
Check yourself
A solar cooker is painted black INSIDE because black…
The best absorber makes the best oven floor.
A thermos flask keeps tea hot using…
One flask, all three roads blocked — the complete heat-transfer exam in a bottle.
Kettles and cooking pans are kept SHINY outside so they…
Dull black surfaces are good RADIATORS too — shine keeps the heat home.
- absorbs the most radiation, getting hottest — correct
- hides the food
- is easy to clean
- vacuum (blocks conduction & convection) + silvered walls (block radiation) — correct
- a heater inside
- very thick glass alone
- radiate away less heat and stay hot longer — correct
- look expensive
- reflect the kitchen light