Efficiency of an Incandescent Light Bulb

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Efficiency of an Incandescent Light Bulb

Alex Mendez

November 4, 2008


The purpose of this lab was to examine the conversion of electrical energy to light and thermal energy as well as the efficiency of incandescent light bulbs.


To design this experiment we need to have a jar with water, temperature, and an voltage source. First, we poured 200 mL of water into a beaker then poured into a cup. We then stir up the water and measured the initial temperature of the water. Then attached the current wires from the voltage source and set it at 12 [V]. We allowed the current run through the wires for 600 seconds, which is also equivalent to 10 minutes. After the time we measured the final temperature.


|V (Volts) |(Amps) |T (s) |M (g) |T (˚C) |Ti (˚C) | |11.2 |2.2 |600 |2008 |22 ˚ |44˚ |


• Calculate electrical energy E delivered to the incandescent light bulb.

Express your result in Joules [J]

• Convert your result into calories [cal]

• Calculate the amount of heat absorbed by water and plastic jar.

Express your result in calories [cal]

• Calculate efficiency of the incandescent light bulb. Express your result in %

Question: Comparison of Fluorescent and 75-W Incandescent Light Fixtures

1. The fluorescent light bulb technology is different because it is more cost efficient and one bulb last longer. The incandescent light bulb initial cost is cheaper, but in the long run it would take about 13 regular light bulbs to last the same length as a fluorescent one. Not only does it save money on the purchase side, but it also saves money by not using that much electricity. A fluorescent light bulb uses 18 watts and a regular bulb is 75 watts.

2. Efficiency for a conventional...
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