When my children were young, my wife suggested that we run a fan in their room to drown out the background noise. If we ran the 100 Watt fan for 8 hours, every day for a 365 day year... how much would this cost annually if electricity cost $0.10 per kWh? 2. The battery in your car is a lead-acid battery. How many volts is it? How many cells (separate batteries kind of like the 9V) is it? 3. If you rub a balloon on your hair two things will happen: your hair will stand up and the balloon will stick to the wall. Explain why both things happen. 4.Explain what a short circuit is. 5. When a light bulb burns out, it's filament breaks, which is basically the same thing as removing the bulb. 20 years ago, when one bulb burned out in a strand of Christmas lights the entire strand would go out, but now it takes a few bulbs to burn out before the entire strand will go out. How did they achieve this? 6. If you have a 60W and a 40W light bulb which bulb has a higher resistance? 7. Some furnace filters that you buy for your home are called electro-static. How do they work? Are they worth the extra money? 8. How much voltage does it take to make electricity jump a one inch gap in air? How much voltage difference is lightning then? 9. Is the purpose of lightning rods to attract lightning?

10. Describe the parts of a lightning bolt.

11. If you decrease the resistance in a circuit and keep the voltage the same, what happens to the current? Why are resistors used in circuits?

12. During the summer, I rarely get a shock when I walk across my carpet and touch a doorknob. However, during the cold winter months, this happens much more often. Why would this be?

13. Birds perch high on power lines and are not harmed. How can this be?

14. A central air conditioning unit can typically be 3500 Watts. On a hot summer day, it might run a total of 8 hours. If electricity costs $0.10 per kWh, how much would it cost to run the air conditioner per day, per week, or for the month?

VAN DE GRAFF GENERATOR

Watch the following video (or similar video regarding a Van de Graff generator) prior to reading and answering the following questions:

http://www.youtube.com/watch?v=rNEY3Yv9kC8

A Van de Graaff generator is an electrostatic device that uses a moving nonconductive belt to carry electric charge into a hollow metal sphere. This sphere is insulated from the ground and can accumulate charge until enormous voltages are reached. Small Van de Graaff generators are exciting novelties while large ones are used in research and industry. These are often used in physics classrooms across the world to demonstrate electrostatic discharges.

1. A typical Van de Graaff generator uses a rubber belt to carry negatively charged electrons from its base to the sphere. As the belt passes through the sphere, a metal brush touches it. Electrons leave the belt and flow through a wire to the surrounding sphere. Why do they flow onto the outside of the sphere rather than staying near the belt?

2. As negative charge builds up on the sphere, the belt motor begins to strain. What makes it progressively more difficult for the motor to move the belt?

3. The amount of charge that can build up on the sphere depends on the sphere's surface. Why is it important that there be no sharp points on the sphere?

4. As you move your hand close to the negatively charged sphere, your hand becomes somewhat positively charged and a spark may leap from the sphere to your hand. Why does your hand acquire a positive charge, and from where does it come? (Keep in mind... protons don't move... electrons move)

5. If you insulate yourself from the ground and put your hand on the sphere, negative charge will accumulate on you as well as on the sphere. Explain why your hair stands up.

FUSES & CIRCUIT BREAKERS

Electrical circuits in your car provide electricity to your headlights, dashboard, windows, and other components. Fuses located in a fuse box protect these circuits. In a modern home, a similar protection is provided by a circuit breaker.Read through the material at howstuffworks.com on circuit breakers and answer the following questions in your OWN words.

http://electronics.howstuffworks.com/circuit-breaker2.htm

6. How does a fuse function?

7. How does a modern circuit breaker switch work?

COST CALCULATION FOR LIGHT BULBS

A practical aspect of this unit is the ability to calculate how much electricity costs and how we can save money. When I started teaching physics, my kitchen had 10 floodlights recessed in the ceiling... each being 75 Watts. The lights are on an average of 3 hours a day for 365 days a year and electricity costs approximately $0.10 per kWh.

8. How much does it cost annually to use the 10 incandescent floodlights in my kitchen?

9. Based on these calculations (yes... I'm not ashamed to say I actually did the math), I purchased 10 LED replacement bulbs - each rated at 15 Watts. Based on the information above, how much would it cost annually to use these bulbs?

10. How much money is saved annually by using LED bulbs in my kitchen? (this has actually motivated me to replace all of my light bulbs and look for other ways to reduce electricity costs in my home

Clear explanation please.