Wikibooks: School Science/The Indian rope trick (magnetism)

• Format: Book
• Language: English
• Subjects: Indian; North Pole; South Pole; The Bench; South pole
• Online Access: https://en.wikibooks.org/wiki/School_Science/The_Indian_rope_trick_(magnetism)

Experiment setup This is a How to about a School science experiment Indian rope trick (magnetism) . This is a good demonstration that is used in schools to teach the idea of magnetic materials. It can be fiddly to set up but it s worth the effort. = Materials = Magnet Sticky tape or Duct tape Samples of materials to insert in the gap = Method = lamp the magnet in the clamp stand. ie some cotton onto a paper clip and allow the paper clip to stick to the magnet. ently pull the cotton down so that there is an air space between the paper clip and the magnet and then stick it to the bench with some sticky tape. This demonstration works best if the air gap is sufficiently large that the paperclip is only just held up by the magnet. It takes a fair amount of adjustment to get it perfect. nsert a non material into the air gap e.g. a piece of or a sheet of . The paper clip stays up. nsert a ferromagnetic material such as an nail or sheet of and the paperclip falls. = How does it work? = The that holds the paperclip up is due to an induced magnetic forming in the clip. In other words if the south pole of the magnet is down for example the s in the paper clip orient themselves so that the top end of it becomes a north pole the bottom a south. Like poles repel and opposite poles attract. The attraction of the magnet for the (induced) north pole is greater than the repulsion of the induced south one because it is closer. That holds the paper clip up. If the north pole of the permanent magnet is down the same argument applies with north and south interchanged. You can verify that the paper clip has become a miniature magnet by the way by showing that iron filings will stick to it but don t let the filings get on the big magnet or you will have a job cleaning it! Why is the magnetic field of the bar magnet strongest near its poles? This can be visualized in terms of lines of force that emanate from it as can be seen by sprinkling iron filings on paper. These lines are called s. The closer the lines are together the bigger the ...