1. 10.3 Charges at Work (Pages 418-427)

2. Learning Goals
I can use electrostatics to explain why lightning strikes happen.
I can explain how lightning rods work.
I can describe practical uses of electric charges, including electrostatic precipitators, electrostatic spray painting, Van de Graaff generators and radiation dosimeters.

3. A lightning rod is a metal sphere or point that is attached to the highest part of a building and connected to the ground.
A lightning rod reduces the likelihood of a lightning strike. If there is a lightning strike, the lightning is more likely to strike the lightning rod than the building it protects, and then to be conducted to the ground.

4. An electrostatic precipitator removes unwanted dust particles and liquid droplets from a flow of gas.

5. An electrostatic separator uses induced charges to separate particles that have different masses.
A Van de Graaff generator is capable of generating very large charges.

6. In the dark, selenium is only a fair conductor
In the dark, selenium is only a fair conductor. When exposed to light, it becomes a very good conductor. Selenium-coated drums are used in photocopiers, laser printers, and scanners.
A radiation dosimeter is a small device that detects and measures exposure to radiation.

7. Lightning

8. Lightning

9. Lightning

10. Lightning Rods
Lightning rod: a metal sphere or point, attached to the highest part of a building and connected to the ground
Video: How lightning rods work

11. Electrostatic Precipitators
Electrostatic precipitator: a type of cleaner that removes unwanted particles and liquid droplets from a flow of gas

12. Electrostatic Spray Painting
Paint and object to be painted are given opposite charges  attraction between paint and object
Minimizes wasted paint and ensures even coat of paint
Especially useful for curved objects

13. Van de Graaff Generators
Van de Graaff generator a device that accumulates very large charges
Rubber belt carries electrons away from the sphere, producing a build- up of positive charge

14. Photocopy Machines Video: How Photocopy Machines Work
Discovery Channel Video: Laser Printers

15. Radiation Dosimeters
Radiation dosimeter: a small device that detects and measures exposure to radiation
When radiation is present, it knocks electrons from gas atoms in the dosimeter
The charged particles are detected by a piece of metal in the dosimeter that behaves like an electroscope

16. Video1: How Electrostatic Precipitators Work Video2: How Electrostatic Precipitators Work Video3: Electrostatic Spray Painting Video4: MythBusters Build a Van de Graaff Video5: Quartz Fiber Radiation Dosimeter

17. Practice
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