Conduction, convection, and radiation · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Conduction, convection, and radiation

Science · Energy · ages 12-13
Name ______________________   Date ____________

  1. A metal rod and a wooden rod are the same length and diameter. One end of each is placed in a flame. Which rod conducts heat to the other end faster?

    • The wooden rod
    • The metal rod
    • Both at the same rate
    • Neither conducts heat

  2. A 200 g copper block (c = 0.385 J/g°C) is heated from 20 °C to 80 °C. How many joules of energy are transferred to the block?

    Answer: ______________

  3. Water has a specific heat capacity of 4.18 J/g°C. How many joules are needed to raise the temperature of 150 g of water by 10 °C?

    Answer: ______________

  4. Convection can occur in solids because particles vibrate and pass energy to neighbors.

    Circle one:   True   False

  5. What is the name for a loop of rising warm fluid and sinking cool fluid?

    • Conduction chain
    • Convection current
    • Radiation beam

  6. A cup of tea starts at 90°C in a 20°C room and cools down to 40°C. What happens to its rate of heat loss as it cools?

    • It speeds up, because the tea has less energy left
    • It slows down, because the temperature difference gets smaller
    • It stays exactly the same the whole time

  7. Why do people often wear light-coloured clothes in hot, sunny weather?

    • Light, shiny surfaces reflect more radiation and absorb less
    • Light colours stop convection currents from forming
    • Light colours make particles vibrate less

  8. Why does a metal pan handle get hot fast, while a wooden handle on the same pan stays cool?

    • Metal has no particles to vibrate
    • Metal reflects all the heat away
    • Metal has free electrons that carry heat energy fast

  9. Ravi says convection can only happen in liquids, never in gases. Is Ravi correct?

    Circle one:   True   False

  10. A 90°C pot and a 40°C pot both sit in a 20°C room. Which one loses heat to the room faster?

    90°C pot940°C pot4
    • They lose heat at exactly the same rate
    • The 40°C pot, because it has less energy left to lose
    • The 90°C pot, because its temperature difference from the room is bigger
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Answer key

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

Conduction, convection, and radiation W1-mt_ySnOkVIu22-s1

  1. The metal rod · Metals have free electrons that carry energy quickly. Wood has no free electrons and contains air pockets that slow conduction.
  2. 4620 · Use Q = mcΔT. Mass is 200 g, c is 0.385 J/g°C, ΔT is 60 °C. 200 × 0.385 × 60 = 4620 J.
  3. 6270 · Q = mcΔT = 150 g × 4.18 J/g°C × 10 °C = 6270 J.
  4. False · Convection requires fluid movement. In solids particles vibrate but cannot flow. That is conduction, not convection.
  5. Convection current · Warm, less dense fluid rises and cooler, denser fluid sinks, making a loop called a convection current.
  6. It slows down, because the temperature difference gets smaller · As the tea's temperature gets closer to the room temperature, the gap between them shrinks, so heat transfers more slowly.
  7. Light, shiny surfaces reflect more radiation and absorb less · Dark, matt surfaces absorb infrared radiation well, but light, shiny surfaces reflect more of it, so you heat up more slowly.
  8. Metal has free electrons that carry heat energy fast · Metals conduct heat well because free electrons move through them and carry energy quickly, on top of particle vibrations.
  9. False · Convection happens in gases too. Warm air rises above a radiator and cooler air sinks to replace it, just like in a liquid.
  10. The 90°C pot, because its temperature difference from the room is bigger · The 90°C pot has a bigger temperature difference from the room, so heat transfers out of it faster.
Worksheet · LightMySky