Year 7 Science · Unit 3 · Lesson 14
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Learning Goals
Practical investigation
Maya wants to test how distance changes the pull of a magnet. She places a pile of steel paper clips on the table, lays one sheet of paper over them, and lowers a bar magnet onto the sheet. She counts how many clips the magnet lifts. She then repeats this with 2 sheets, then 3, then 4, increasing the distance between the magnet and the clips each time. Her results are: 1 sheet = 6 clips, 2 sheets = 4 clips, 3 sheets = 2 clips, 4 sheets = 0 clips.
(a) Describe the pattern in Maya's results. What happens to the number of clips lifted as the number of sheets increases, and what does this tell you about the magnetic force?
(b) In Maya's experiment, what is the one variable she changes, and name one thing she must keep the same to make it a fair test?
Because… chain
Fill in the missing effects in the boxes below. Each cause leads to the next step in the chain. Then write the overall outcome at the bottom.
Overall outcome, why does adding sheets of paper make the magnet lift fewer clips?
1. You have two bar magnets. When you bring end A of the first magnet near end C of the second, they attract. When you bring end A near end D, they repel. What can you say about the poles A, C and D? Use the rule of polarity.
2. A bushwalker uses a compass to find north. Explain how the compass needle works, and why it counts as a magnet behaving as a non-contact force.
Wrap Up
In one sentence, what was the main idea of this lesson?