my name & no.matrik

Mrs Lee Hooi Sean D 20112054699

2012年11月12日星期一

Unit 3 Magnets

http://www.youtube.com/watch?v=oHMSgKKi3jcMagnet Introduction and how it works ~

Students learn that magnets can attract other magnets or objects without touching or through various substances. They also learn that magnets can also repel each other without touching.

Transcript: These are all magnets. Magnets can do some amazing things and they have some very interesting powers or forces. They're kind of like a scientific super hero. Here are some of our super hero's interesting powers.


Magnets can pull or attract certain types of metals toward them. Iron is the most common type of metal that is attracted to magnets. The magnet pulls an object made of iron towards it until the object sticks to the magnet. The magnet doesn't even have to touch the object to pull it!


Magnets have an area surrounding them in which their powers will work. This area is called a magnetic field. We can demonstrate the distance of this magnet's field of power by placing it on this board containing tiny bits of iron. The magnet will attract all the iron within its magnetic field. In this case, this magnet's field extends about ½" from the end of the magnet.


A magnet's force can even work through other objects. It can pull through paper, plastic, glass, or water to name a few. This again shows how a magnet can use its super hero-like pulling ability without actually touching the object.


When our superhero magnet attracts things made out of iron, it shares some of its magnetic powers with those objects. The magnet turns the objects it is touching into magnets too. The objects only keep this power for a short time, usually only as long as they are touching the magnet itself. This paper clip chain demonstrates that the magnet is also turning the paper clips into magnets. The closer to the magnet that the paperclips are located, the stronger the paper clip's magnetic force will be. As the chain gets longer, the magnetic force gets weaker.


Our super hero does not share his magnetic powers with all types of metals. For example, he won't stick to aluminum or stainless steel. Magnets also won't stick to objects made out of wood or glass. As we said before, iron is the metal most commonly attracted to magnets, like in this refrigerator.


Magnets have two poles. These poles are called the north pole and the south pole. Bar magnets, like this one, are often labeled with an N for the north pole and an S for the south pole. The poles are the places where a magnet's force is the strongest. Magnet's poles are attracted to their opposites. For example a north and a south pole will pull or stick together. However, when you put two of the same poles together, like a north to a north, or a south to a south, you will discover another one or our magnet's super-hero abilities. When the magnetic fields of two like or same poles come close together, they push away from each other, or repel. These ring magnets on a stick are demonstrating like poles repelling. You can push or move magnets around the table without touching them, by using the pushing power of like poles.


We've learned that our super hero magnet has some pretty amazing powers. Magnets can move objects without touching them. They can attract or pull objects toward them, and they can push or repel other magnets away.

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