DENJIRO: This is an extremely powerful magnet called a neodymium magnet. If I bring the magnet close to these paper clips... This is the kind of power this magnet has. But a neodymium magnet has a weakness too.
There are two kinds of magnets on this metal bar. One is the powerful neodymium magnet, and the other is a less powerful magnet called ferrite magnet. We’ll use the magnetic force of each to make a paper clip float. Now, let's heat the metal bar using a burner. What will happen?
BOY: The paper clip fell!
DENJIRO: The paper clip pulled by the more powerful neodymium magnet fell first. When the burner heats up the magnet, the particles inside the magnet move vigorously. The direction of the magnetic force that was aligned before becomes misaligned. This is what causes the magnet's magnetic force to decrease.
The temperature at which the magnet begins to lose its force is called the Curie temperature. For a ferrite magnet, this is about 450 degrees Celsius, and about 330 degrees Celsius for a neodymium magnet. Although the neodymium magnet has a much stronger magnetic force than the ferrite magnet, it is actually weaker against heat. Here, we have a toy that exploits this characteristic of magnets. I'll light the candle.
BOY: Interesting!
DENJIRO: Here's how it works. The magnet gives the two wires a magnetic force. When one of the wires gets heated by the candle, it loses its magnetic force. Consequently, the other wire gets attracted by magnet. Once that wire loses its magnetic force due to heat, the other that has cooled down and regained its magnetic force gets attracted to the magnet. This cycle repeats itself.
I hope energy will bring you all happiness. Our magic word is "Happy Energy!"
Негізгі бет The Weakness of Magnets / Mr. Denjiro's Happy Energy!
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