3.3 microscope measurements and calculations

What do we use to measure the size of objects when using a light microscope?

An eyepiece graticule

What is the graticule?

(4 points) BLURT

• A glass disc that is placed in the eyepiece of a microscope

• A scale is etched on the glass disc

• The scale is 10mm long and is divided into 100 subdivisions

• The scale is visible when looking down the eyepiece of the microscope

What can the scale on the eyepiece graticule not be used for?

Cannot be used directly to measure the size of objects under a microscopes objective lens because each objective lens will magnify to a different degree

How do you calibrate an eyepiece graticule?

You need to use a special microscope slide called a stage micrometer

This slide also has a scale etched onto it

Usually the scalle is 2mm long and its smallest subdivision is 0.01mm