Year 8 Science · Unit 2 · Lesson 16
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Learning Goals
Real-world context
Australia is one of the world's top producers of gold and copper, according to Geoscience Australia's Australian Gold and Copper Assets report (2023). Both metals conduct electricity, yet they are used for different electrical components inside a modern smartphone. Gold is found in the circuit board's contact points, while copper makes up the power cables and internal wiring.
(a) Both gold and copper conduct electricity, yet the phone uses each metal for a different electrical purpose. Identify one specific property (other than conductivity) that differs between gold and copper, and explain how that difference determines where each metal is used inside the device.
(b) Predict what would happen to the electronics industry if all gold used in circuit board contacts were replaced with copper. Consider both material properties and real-world outcomes in your answer.
Read the graph
The bar chart below shows the relative electrical conductivity of six common metals (Silver = 100). Study the chart, then answer the questions below.
(a) Which metal shown in the chart is the best electrical conductor?
(b) Silver conducts electricity better than copper, yet copper, not silver, is used for household wiring. Using information from the chart and your own knowledge, explain why.
(c) Iron is far cheaper than copper, yet it is not used for electrical wiring. Using the chart, explain why iron would be a poor choice for wiring despite its low cost.
1. A student says: "All metals conduct electricity, so it doesn't matter which metal you use for wiring." Use evidence from the bar chart to explain why this statement is misleading.
2. Iodine is used as an antiseptic to sterilise wounds. Using the property-use reasoning framework (property → why it matters → use), write a full explanation for this choice.
Wrap Up
In one sentence, what was the main idea of this lesson?