Explain why a metal spoon left in a hot bowl of soup feels hotter to the touch than a wooden spoon left in the same bowl of soup.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Two spoons, one made of metal and one made of wood, are both placed in a bowl of hot soup for several minutes. A person picks up each spoon by its handle.
Model answer (5 marks)
Heat energy is transferred from the hot soup to both spoon handles by conduction.
Metal is a better conductor of heat than wood.
In metals, free (delocalised) electrons transfer thermal energy quickly along the spoon.
In wood, energy can only be transferred by vibrations of particles being passed to neighbouring particles, which is a slower process.
More thermal energy reaches the metal spoon handle, so it feels hotter to the touch.
Metal is a better conductor of heat than wood.
In metals, free (delocalised) electrons transfer thermal energy quickly along the spoon.
In wood, energy can only be transferred by vibrations of particles being passed to neighbouring particles, which is a slower process.
More thermal energy reaches the metal spoon handle, so it feels hotter to the touch.
Examiner tips
- Use the word "conduction" to show understanding of the transfer mechanism. Mention the role of free electrons in metals. Explain the slower vibrational transfer in wood. Finish with the consequence for the handle temperature.
Common mistakes
- Confusing heat with temperature. Saying the soup heats the spoon by radiation. Forgetting to mention free electrons or vibrational transfer.
Mark scheme (5 marks)
- Heat energy is transferred from the hot soup to both spoon handles by conduction
- Metal is a better conductor of heat than wood
- In metals, free (delocalised) electrons transfer thermal energy quickly along the spoon
- In wood, energy can only be transferred by vibrations of particles being passed to neighbouring particles, which is a slower process
- More thermal energy reaches the metal spoon handle, so it feels hotter to the touch
Related
- All WJEC A-Level Physics (Wales) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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