Energy and Lighting Lab



Instructor Outline: UM Physics Demo Lab 07/2013Energy and LightingLab length: 70 minutesLab objective: To have the students perform an engineering trade study to understand the pros and cons of various home lighting technologies and then explore the feasibility and cost of using solar photovoltaic cells as a source of domestic electrical power.MaterialsRegular (incandescent) 40 W light bulbRegular (incandescent) 60 W light bulbCompact fluorescent 40 W equivalent bulbLED light bulbDigital voltmeter with alligator leadsSolar panelLamp bases with amp cordsInduction ammeter – clamp-onLight/lux meterMeter StickClear RulerCalculatorRag (for handling warm light bulbs)Introduction stage: 10 minutes – LectureThe concept of an engineering trade study as a tool to determine the benefits, drawbacks and relative costs of various engineering options (in this case choice of home lighting options) is introduced. The calculation of power in a circuit is reviewed and the kilowatt-hour as a convenient unit of energy is introduced.Exploration stage: 30 minutes - Group Lab workThe students quantify the power consumed by incandescent, compact fluorescent and LED lighting systems and then use their data, along with the cost of electricity to calculate the cost per hour of illumination for each lighting technology. They then estimate and compare the annual cost for each lighting technology. They then measure the relative light output of each lighting device with both an uncelebrated photovoltaic cell and a calibrated light meter and compare the results.Application stage: 30 minutes – Group Lab WorkThe students then measure the power output of a photovoltaic cell when exposed to illumination comparable to sunlight and measure the efficiency for the cells. They then estimate the area required for an array of photovoltaic cells capable of producing the power output of a typical fossil fuel powered power plant.Concepts Developed:Engineering trade studies as a tool for making informed technical decisions.Kilowatt-hours as a unit of energy.Lighting energy efficiency can be greatly improved by replacing incandescent bulbs with new technologies such as compact fluorescent tubes and LEDs.Photovoltaic cells produce electricity directly from sunlight and can be used for practical power generation. The major impediment to their more widespread use is cost, not technical feasibility.Suggested Demonstrations:Shaker Flashlight—demonstrates high efficiency of LEDs for producing light and introduces the idea of power generation from mechanical work by induction for the upcoming motors and generators lab. ................
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