2.1.1: Eyepiece Graticule

Question 1

What is an eyepiece graticule?

Answer 1

A scale on a glass disc inside light microscopes used to measure the size of objects viewed under the microscope.

Question 2

What must be done each time the objective lens is changed?

Answer 2

The eyepiece graticule must be calibrated to determine the distance between each division at the new magnification.

Question 3

What is the value of one division on the micrometer?

Answer 3

One division on the micrometer equals 10 micrometers (um).

Question 4

How do you calculate the size of one division on the eyepiece graticule?

Answer 4

If two divisions fit into one division on the micrometer, then one division on the eyepiece graticule is 5 um (10/2 = 5 um).

Question 5

What are the steps to calibrate the eyepiece graticule?

Answer 5

Step 1: Line up the stage micrometer and eyepiece graticule while looking through the eyepiece.
Step 2: Count how many divisions on the eyepiece graticule fit into one division on the micrometer scale.
Step 3: Use the micrometer’s division value (10 um) to calculate the value of one division on the eyepiece graticule.