1. The document discusses electrostatic equilibrium and how excess charge accumulates on the outer surfaces of conductors, especially at points with smaller radii of curvature. 2. It then explains how static electricity builds up in storm clouds and the process of how lightning occurs when the electrical fields become strong enough to ionize the air and allow a discharge between the cloud and the ground. 3. Lightning rods are described as providing a path for lightning to safely discharge into the ground and avoid going through buildings.

1. Everyday Electricity February 26th, 2009

2. Conductors in Electrostatic Equilibrium Electrostatic equilibrium When no net motion of charge is occurring within a conductor Electrical field is 0 everywhere inside conductor Any excess charge resides entirely on the conductors outer surface Electrical field just outside a charge conductor is perpendicular to the conductor’s surface Charge tends to accumulate where the radius of curvature of the surface is smallest (sharp points)

3. Why does it matter? When a conductor is in electrostatic equilibrium charge will collect at the sharpest points When enough charge accumulates it will suddenly discharge

4. Van de Graaff Generator The top of the generator is a sphere so that large amounts of charge can build up without discharging (they would discharge if there was a point on top)

5. Static Electricity & Lightning Lightning occurs because of a polarization of the storm clouds The bottom of the cloud develops an excess of Negative charge A positive charge is then induced on the surface of the earth

6. As the static buildup during the storm becomes stronger the electrical fields around the cloud become strong enough to ionize the air, making it able to conduct electricity (becomes a conductive plasma) A lightning bolt begins when a step leader of excess electrons begin to move towards the ground. These electrons push away even more electrons from the Earth’s surface causing more positive charge to build up

7. The built-up positive charge can begin to migrate upward forming a streamer. When the streamer and step leader meet a complete path is formed and lightning can strike!

8. Lightning Rods Lightning rods are often attached to the tops of tall buildings The rod is made of metal and then attached to a wire that is buried deep in the ground This gives the lightning an easy path to the ground and it will avoid going through the building

11. The Leyden Jar Earliest form of a battery Charged by static electricity Leyden Jar Demonstration