3.3 - Microscope Measurements And Calculations

Question 1

How can you measure the size of objects using a light microscope?

Answer 1

When using a light microscope, we can measure the size of objects using an eyepiece graticule.

Question 2

Why can’t an eyepiece graticule not be used directly to measure the size of objects under an objective lens?

Answer 2

The scale on the eyepiece graticule cannot be used directly to measure the size of objects under a microscope’s objective lens because each objective lens will magnify to a different degree.

The graticule must first be calibrated for a particular objective lens.

Question 3

How do you calibrate and eyepiece graticule?

Answer 3

To calibrate and eyepiece graticule you need a special microscope slide called a stage micro meter. This slide also has a scale etched onto it.
When the eyepiece graticule scale and the stage micrometre scales are lined up it is possible to calculate the length of the divisions on the eyepiece graticule.

Question 4

How to calculate the scale for different objective lenses?

Answer 4

To calculate the scale for different objective lenses divides the differences in magnification.