MYP Physics Static Electricity Notes

What Is Static Electricity?

1. Static electricity is the set of effects you observe when electric charge builds up on objects and then stays in place (instead of flowing continuously as a current).
2. It explains everyday experiences such as a small shock after walking on a carpet, sparks when removing a synthetic sweater, or a balloon sticking to a wall.
3. Static electricity is usually noticed when objects attract, repel, or suddenly discharge charge.

Static Electricity Is Charge Imbalance, Not "Extra Electricity"

1. All matter is made of atoms containing positively charged protons and negatively charged electrons.
2. Most objects are overall neutral, meaning they have equal total positive and negative charge.
3. Static electricity occurs when this balance changes locally: one object ends up with an excess of electrons (becoming negatively charged) and another ends up with a deficit of electrons (becoming positively charged).
4. Importantly, the object that gains electrons and the object that loses electrons gain equal and opposite charge because each transferred electron leaves one surface and arrives at the other.

Rubbing Materials Transfers Electrons

1. Many static effects start when two different materials come into contact and separate, especially when they are rubbed together.
2. At the surfaces, some electrons can be pulled away from atoms and transferred to the other material.
3. Rubbing increases the interaction between surfaces, so it usually increases the number of electrons transferred.
4. A classic example is rubbing a balloon on hair or a sweater:
   1. The balloon typically gains electrons and becomes negative.
   2. Hair or wool typically loses electrons and becomes positive.

Why Your Hair Stands Up

1. After rubbing a balloon on hair, each hair strand can be left with a small positive charge.
2. Because like charges repel, the hairs push away from each other, so they separate and can stand up.

The Triboelectric Series Predicts Which Material Becomes Positive Or Negative

1. Different materials have different tendencies to gain or lose electrons when in contact.