Here's why:
* Insulators have tightly bound electrons that are difficult to move. This makes it hard for electricity to pass through them.
* Conductors have loosely bound electrons that can move freely. This allows electricity to flow easily through them.
However, there are some exceptions:
* Some rulers are made of metal, which is a conductor. These rulers would allow electricity to flow through them.
* Even plastic rulers can become conductive under certain conditions, such as high temperatures or exposure to static electricity.
In general, you should assume that a ruler is an insulator unless you know for sure that it is made of metal.
