By: Merida S.
The purpose of this experiment was to find out how different wattages of incandescent light affected bacteria. To start the experiment, a small sample of pond water was collected. A culture medium was cooked from chicken broth and gelatin. This solution was then poured in to petri dishes, allowed to gel, then was inoculated with bacteria. The petri dishes were then placed under lamps of different wattage and were allowed to sit undisturbed. Every day, the bacterial colonies were counted and measured. When the experiment was finished, it was found the lamp with 60 watts grew 100 bacterial colonies, therefore was the best amount of light. The other amounts of light did not grow bacteria all that well and were very inefficient in terms of growing bacterial colonies. The 15 watt lamp grew 7 colonies, the 40 watt lamp grew 4 bacterial colonies, the 100 watt lamp grew 2 bacterial colonies, the dark area grew 2 bacterial colonies, and the 25 watt lamp grew no bacterial colonies, making it the most inefficient amount of light. Under the lamp with a 60 ­ watt bulb, 100 colonies grew. It was 5000% of the control (0 watts), which grew 2 colonies. Under the lamp with a 15-watt bulb, 300% of the control grew. Under the lamp with a 25 - watt bulb, there were no colonies, so 100% less grew than the control. Under the lamp with a 40 ­ watt bulb, 100% of the control grew. Under the lamp with the 100 ­ watt bulb, 100% of the control grew.