http://www.ck12.org Chapter 5. Energy
5.64 Static Electricity and Static Discharge
- Describe static electricity.
- Explain static discharge.
- Outline how lightning occurs.
You’re a thoughtful visitor, so you wipe your feet on the welcome mat before you reach out to touch the brass
knocker on the door. Ouch! A spark suddenly jumps between your hand and the metal, and you feel an electric
shock.
Q:Why do you think an electric shock occurs?
A:An electric shock occurs when there is a sudden discharge of static electricity.
What Is Static Electricity?
Static electricityis a buildup of electric charges on objects. Charges build up when negative electrons are transferred
from one object to another. The object that gives up electrons becomes positively charged, and the object that accepts
the electrons becomes negatively charged. This can happen in several ways.
One way electric charges can build up is through friction between materials that differ in their ability to give up or
accept electrons. When you wipe your rubber-soled shoes on the wool mat, for example, electrons rub off the mat
onto your shoes. As a result of this transfer of electrons, positive charges build up on the mat and negative charges
build up on you.
Once an object becomes electrically charged, it is likely to remain charged until it touches another object or at least
comes very close to another object. That’s because electric charges cannot travel easily through air, especially if the
air is dry.