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# Grab your lab notebook. Be seated and silent when the bell rings.

## Presentation on theme: "Grab your lab notebook. Be seated and silent when the bell rings."— Presentation transcript:

Grab your lab notebook. Be seated and silent when the bell rings.

Rub a balloon on your head (this won’t work if you are the king or queen of gel). Pull the balloon away from your head slowly. Notice the attraction between your hair and the balloon?

 Attractive force: Positive and negative charges like to be together. When they are separated, they have a tendency to jump back together.

Slowly... Try to bring the balloons close together.

What happened when you brought the two balloons close together? Why?

 Opposite charges attract and like charges repel.

Now, rub the balloon on your hair again. This time, hold the balloon close to your partner’s hair. What happened? Why? Hold the balloon close to your hair again just to make sure the trick still works.

 Protons (+)  Neutrons (0)  Electrons (-)  Hmmmm....  So what happened when you rubbed the balloon on your hair and held it close to your partner’s hair? REMEMBER ATOMS?

 Electrically neutral: Having equal numbers of positive and negative charges.

STATIC ELECTRICITYCURRENT ELECTRICITY  Static electricity refers to charges exerting forces on other charges.  Static means not moving.  All of the balloon examples so far have been static.  Current electricity refers to charges which are in constant motion.

Try the following magic tricks.

 Rub the balloon on your clothes, then try to stick it to the wall. ALSO TRY...  Pepper trick  Paper trick  Cup trick  Water trick

Attraction is weaker than repulsion. Scientists say the negatively charged balloon has induced a charge in the paper. The paper contains an induced charge.

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