Year 8 Science · Unit 2 · Lesson 17
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Learning Goals
Predict and reason
Scenario
A solar panel manufacturer needs a material that can convert sunlight into electricity efficiently and is cheap enough for mass production. The engineer narrows the search to the five elements studied in this lesson: copper (Cu), aluminium (Al), helium (He), silicon (Si), and carbon (C). She must choose one element as the core material for the panel's photovoltaic cells.
(a) Predict which of the five elements is most suitable for the photovoltaic cells, and state the key property that makes it suitable.
(b) Explain why at least two of the other four elements would not be suitable for this role. Use specific properties from the lesson in your answer.
Compare two
Complete the table to compare copper and aluminium as electrical conductors. Use what you know from the lesson, some cells will require you to think carefully about relative differences.
| Feature | Copper (Cu) | Aluminium (Al) |
|---|---|---|
| Electrical conductivity (relative) | ||
| Density (heavy or light?) | ||
| Relative cost | ||
| Corrosion resistance | ||
| Main uses in the electrical industry |
1. An engineer is designing long-distance power lines that need to run between cities. She considers using copper wire, but switches to aluminium instead. Using your comparison table, explain why aluminium might be a better choice for long-distance overhead power lines despite its slightly lower conductivity.
2. Diamond is the hardest natural material on Earth and is used in cutting and drilling tools. Graphite is so soft it is used in pencil lead and as a lubricant. Both are made entirely of carbon atoms. Using the idea of allotropes, explain why the same element can have such drastically different physical properties.
Wrap Up
In one sentence, what was the main idea of this lesson?