10.3 Charges at Work: (Pages 418-427) Homework: Page 428 # 3, 4, 7, 8 Key Concepts: (Page 428)

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. Lightening Rods

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

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.

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. Watch This A radiation dosimeter is a small device that detects and measures exposure to radiation.

Lightning: 1. Visualizing Lightning. Draw figure 10.17 on page 419

2. Explain how a lightning rod works. 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 thick, insulated copper wire connects the lightning rod to a metal plate or bare metal cable in the ground. Since the cable is bare, it allows the charges to be conducted into the ground.

3. Why does lightning tend to strike the tallest building nearby? Lightning takes the path of least resistance between a cloud and the ground, usually striking the highest object in an area.

4. What are some of the hazards of a lightning strike? Since the lightning strike has a very large electric current, it can lead to hazards such as forest fires and deaths.

5. Why does lightning follow a jagged path? Lightning follows a jagged path because air currents and turbulence produce regions of differing conductivity for the lightning discharge to follow.

6. List & explain different uses of electrostatics. Electrostatic Precipitator A type of cleaner that removes unwanted particles and liquid droplets from a flow of gas Dust and pollen particles are charged, and then attracted to an oppositely charged or grounded plate When the particles collide with the collection plate, they are neutralized, collected, and removed

6. List & explain different uses of electrostatics. Electrostatic Spray Painting The paint or powder is given a charge as it leaves the nozzle of the sprayer The object to be coated is either grounded or given a charge that is opposite to the charge of the particles in the spray Thus, the particles are attracted to the object being coated, minimizing the amount of over-spray

7. What is a Van de Graaf generator? It is a device that can accumulate or transfer very large charges

8. What function does a Van de Graaf generator play in an atom smasher? The Van de Graaf generator can accelerate particles to very high speeds

9. Why is it important to have a radiation dosimeter if a person works in a facility that has equipment that emits radiation? Since a radiation dosimeter detects and measures exposure to radiation, it would be important to have one in this type of facility in order to determine dangerous/hazardous levels of radiation.