Electricity consumption is a large fraction of our overall energy use

Electricity consumption is a large fraction of our overall energy use

Electricity consumption is a large fraction of our overall energy use. Electricity is generated using both fossil fuels and renewable energy sources. In this assignment, you’ll review the basics of electricity, some energy sources, and examine electricity flow and efficiency. [40 points total]

Conceptual and quantitative problems. You will only receive credit if you show all your work and write legibly.

1 .A circuit includes a 9 V battery and a copper wire of a given length and diameter. You measure the current in the wire to be 1.5 Amperes.

a. What is the resistance of the wire? Your answer should be in Ohms. [1.5 pts]

b. With this battery and wire, how much power can be provided? Report your answer in Watts. [1.5 pts]

c. What changes could you make to the wire to increase the power? [1.5 pts]

d. If you half the resistance of the wire, what is the power output? [1.5 pts]

1

e. If you double the voltage of the battery, what is the power output? [1.5 pts]

2. You have been using a 75W traditional incandescent light bulb in your desk lamp. However, in a SPU 25 section, you have learned about LED light bulbs and decided to replace your inefficient light bulb with a 12W LED that provides the same amount of light.

a. Assuming that you are using your lamp for 5 hours per day and the electricity rate is 15 cents per kilowatt-hour, what is your annual energy cost savings? [2.5 pts]

b. The incandescent bulb cost about $0.75, and the LED bulb cost about $6.00. Based on the energy savings, does the LED bulb save you money in the long run? For more information, visit: http://energy.gov/energysaver/lighting-choices-save-you-money. [2 pt]