Question

1. When you calibrated your eyepiece micrometer, you determined how many microns (µM) each eyepiece unit spans at each magnification level. Say you find that 18 eyepiece units span 100 µM when viewed under the 10x objective. How many microns (µM) long is a cell if it is 2 eyepiece units long under 1000x magnification? Show your work.
2. Diagram the steps in performing an antibiotic disk diffusion assay.

Answer 1

To achieve the calibrated measurement of the sample, multiply the measured value of the sample by the labeled magnification of the objective lens divided by the actual magnification ratio. An ocular micrometer is a glass disk with ruled scale on the surface which is etched in chromium.