Infrared Emission, Absorption and the Temperature of a Body · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Why dark cans cool fastest

Science · Waves, Light & Sound · ages 15-16
Name ______________________   Date ____________

  1. What sets the steady temperature of an object?

    • The point where emission matches absorption
    • The colour of its surroundings
    • The time of day

  2. Which surfaces are best at both emitting and absorbing infrared?

    • Shiny light ones
    • Dark matt ones
    • Transparent ones

  3. Mara says sunlight warming your skin is conduction. Is Mara right?

    Circle one:   True   False

  4. The atmosphere starts absorbing a bigger share of outgoing infrared. What follows?

    • The surface cools down at once
    • Nothing changes anywhere
    • The surface warms until emission restores the balance

  5. A matt black can of water cools faster at night than a shiny one. Why?

    • Black paint holds less water
    • The black surface emits infrared better
    • Night air avoids shiny cans

  6. An object grows hotter. What happens to its infrared emission?

    • It falls away
    • It stays exactly flat
    • It rises steeply

  7. Lee says a resting body stays steady because it stops emitting. What is wrong?

    • It keeps emitting, balanced by equal absorption
    • It stops absorbing instead
    • Resting bodies break thermometers

  8. Two cans sit in the same sun: one matt black, one shiny white. Which heats faster, and why?

    • The white one, because it glows
    • The black one, because it absorbs more sunlight
    • Both identically, since the sun is shared
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Why dark cans cool fastest W1-mt_xwh9uZ8gCl-s1

  1. The point where emission matches absorption · Balance is rest: in equals out, so temperature holds.
  2. Dark matt ones · Dark matt leads at both, while shiny light lags at both.
  3. False · Sunlight crosses empty space, which only radiation can do.
  4. The surface warms until emission restores the balance · Blocked outflow must be matched by stronger emission, which needs warmth.
  5. The black surface emits infrared better · What absorbs well emits well, so black also gives heat away faster.
  6. It rises steeply · Emission climbs very fast with temperature, not gently.
  7. It keeps emitting, balanced by equal absorption · Steady means matched flows, not stopped flows.
  8. The black one, because it absorbs more sunlight · Same sun in, but the black surface takes a bigger share.
Worksheet · LightMySky