Rub various objects to produce electric charges (e.g., plastic wrap and plastic spoons; wool or cotton and balloons). Summarize the results of these experiences.

In experiments on hundreds of different kinds of materials, scientists have found that there are only two types of electrical charge: one type they call positive; the other type they call negative.

Objects that do not have an electric charge are said to be uncharged or neutral.

To learn what rubbing has to do with electricity, study the following drawings.

Everything in the world is made out of tiny particles called atoms. Remember, there are more than 100 different kinds of atoms.

Atoms, in turn, are made up of even tinier particles. Two of the particles making up atoms are electrical: the proton (positive), located in the center or nucleus of the atom; and the electron (negative), which may spin in many different orbits around the nucleus.

Every electron has exactly the same negative charge (-), and every proton has the same positive charge (+).

When an atom has one proton and one electron, it is said to be electrically neutral. (The positive charge of the proton exactly balances the negative charge of the electron.) Normal atoms are electrically uncharged or neutral.

When two uncharged objects are rubbed together, some electrons are rubbed off one object and left on the other -- one object loses electrons, the other gains extra electrons - - and the objects are then electrically unbalanced.

For example, when electrons are rubbed off of neutral atoms, the atoms take on a positive charge because each atom now has more protons than electrons; if neutral atoms gain some
electrons, they take on a negative charge because each atom now has more electrons than protons.

Both static and current electricity can be explained by the movement of electrons from negatively charged atoms to positively charged atoms until a balance is achieved.

Now, stretch a pair of rubber bands at right angles to each other across an aluminum pie pan. Place a plastic bag on a table, rub it vigorously with wool, and hold it up vertically by one edge.

Use your knowledge of protons and electrons to explain what happens when you carry out the following activity:

Hold the pie pan by the rubber bands, press it against the bag, then touch it to one end of a burned-out fluorescent tube. (Note: Be sure that your fingers do not touch the pan.)