Science Buddies: "Ask an Expert"

Hi, I am doing a project that requires me to measure zones of inhibition from paper disks that have been saturated with the liquid to be tested. I have zones of inhibition, but I am wondering how do I measure them?

Do I include the diameter of the paper disk in the measurement? Or do I just measure the radius of the zone of inhibition? Or do I measure the whole circle, and then subtract the diameter of the paper disk?

Help!

Hi Jessica,

You should measure from the edge of the paper disc to the edge of the lawn of bacteria, and measure to the nearest millimeter. This will give you results that you can graph and compare.

Donna Hardy