
Can idea why the answer is (2)?
Can idea why the answer is (2)?
The weight of iron block is lighter when weighed. This is cause by the fact that magnets attract iron.
The weight of the magnetic button is heavier when weighed, so the extra weight must be caused by the magnetic repelling force between the magnetic and the button. So, (b) is wrong.
Hence the answer is (2).
Thank you very much for your help.