A four-foot long wooden 2"x4" (pardon the "English" units) is balanced on a watch glass as seen in the photograph below. A hard rubber rod is charged negative by rubbing it with a woolen cloth, and is held near the wooden beam. The rod attracts the wooden beam, causing it to rotate on the watch glass balance, as seen in an mpeg video by clicking your mouse on the photograph below.
Suppose that we use a use a glass rod that has been charged positive by rubbing it with silk. What will happen when we hold the glass rod up by the 2"x4" in the same way.
When the positive rod is held near the wood, it will:
Click here for Answer #131 after December 16, 2002.
