今天发现了下面这个非常有趣的网站，迫不及待来分享给小朋友们。以静电为例来做个使用说明。建议看完说明（做完题）玩起来更有意思哦。
http://phet.colorado.edu/en/simulation/balloons-and-static-electricity
首先让我们简单了解下概念吧：
- 电荷转移transfer of charge
当某些物体与另一物体摩擦时，电子可能会从一个物体转移到另一物体。 如果一个物体失去一些电子，它会留下多余的质子。 因此，该物体带正电。 如果一个物体获得电子，那么它现在就有多余的电子。 因此，该物体带负电。 电荷转移引起很多物体产生静电。
When certain objects are rubbed against another object, electrons may get transferred from one object to another. If an object loses some electron, it is left with surplus number of protons. Thus, this object becomes positively charged. If an object gains electrons, it now has surplus number of electrons. Thus, this object becomes negatively charged. The transfer of charges is responsible for static electricity in various objects.
比如，用气球摩擦毛衣，电子转移到气球上，气球表面带负电。
- 静电感应Induction
物体内的电荷因受外界电荷的影响而重新分布。正常的物质都带有等量的正电荷和负电荷，因此总体来说是不带电的。如果把带电的物体靠近不带电的导体，例如一片金属，则导体上的电荷将会重新分布。
The charge in the object is redistributed due to the influence of the external charge
比如，用带负电的气球靠近墙（不带电的导体），使墙表面的电荷重新分布，局部略带正电，但是墙作为整体仍是中性的，电荷守恒。
- 静电吸引attraction
不同的电荷相互吸引Unlike charges attract each other
比如，带负电的气球总是爱黏在毛衣上。如果强行把气球和毛衣分开，带负电的气球与墙足够近，就会被吸引到墙上。
- 静电排斥Repulsion
相似电荷互相排斥Like charges repel each other:
比如，两个带负电的气球是互相排斥的。
好啦，来先做题。哈哈。
1．When the balloon is rubbed on the sweater, what might happen?
A．Some positive charges in the sweater will move onto the balloon.
B． Some negative charges in the sweater will move onto the balloon
2. What do you think will happen when the balloon is moved closer to the wall?
Some positive charges in the wall will move towards the balloon
Some negative charges in the wall will move towards the balloon
Some positive charges in the wall will go onto the balloon
Some negative charges on the balloon will go to the wall
3. What do you think the balloons will do?
A. The balloons will move towards each other
B. The balloons will move away from each other
C. The balloons will not move.
想对答案和做不出来的同学，罚你们去玩游戏。自己试试看，答案就出来啦。
The end.
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