Each colony on an incubated plate represents a viable cell that survived UV exposure, so the count tells you directly how effective the treatment was. You collect water samples from a local creek, expose them to a UV lamp, and pull samples at four time points over 24 hours. Each sample goes to a microbiology lab for incubation and counting. With a low-wattage lamp, bacteria decreased at first but then rose above the original count. A higher-intensity lamp produced a steady decline throughout the full 24 hours — consistent with the formula E = W / D-squared, which explains why both lamp power and distance matter.

Incubation provides the warmth, moisture, and air that let living cells grow large enough to observe. In this experiment, creek water samples go to a microbiology lab for incubation, where they are held at a controlled temperature so bacteria multiply into visible colonies. After 24 hours, researchers count those colonies to measure how well UV light reduced the bacterial population.

A UV lamp can disinfect creek water, but its strength determines how well it works. With a low-wattage lamp, bacteria decreased at first — then rose above the original count. Switch to a higher-intensity lamp, and the decline is steady throughout the full 24 hours.