A human RBC is approximately 6 µm in diameter. An unknown bacterium measures 1 ocular space using the oil immersion objective compared to 2 minor spaces on the stage micrometer. A) How big is the unknown bacterium (report in micrometers) ? B) How does its size compare to the RBC (how many times bigger is one versus the other) ?

The following is the formula to determine the size from minor spaces and ocular spaces on the stage micrometer:

Size = Number of minor spaces * 10 micrometer / Number of ocular spaces

A = Number of minor spaces is 2 and the number of ocular space is 1,

Size = 2 * 10 / 1 = 20 micro micrometer. Thus, the size of a bacterium is 20 micrometers.

B = Thus, it can be said that the size of the bacterium is almost 4 times bigger in comparison to a human red blood cell, which is 6 micrometers in diameter.