2.1.3 Measuring objects seen with a light microscope

Question 1

What is an eyepiece graticule?

Answer 1

A measuring device that is placed in the eyepiece of a microscope and acts as a ruler when you view an object under the microscope. The eyepiece scale has to be calibrated (its value worked out)for each different object lens.

Question 2

What is a stage graticule?

Answer 2

-A precise measuring device. It is a small scale that is placed on a microscope stage and used to calibrate the value of eyepiece divisions at different magnifications.

Magnification of eyepiece lens/Magnification of objective lens/Total Magnification/Value of one eyepiece division (ep) (um)
X10	X4	X40	25
X10	X10	X100	10
X10	X40	X400	2.5
X10	X100 (oil immersion lens)	X1000	1.0

Total magnification = magnification of eyepiece lens x magnification of objective lens

Value of eyepiece division = stage graticule (1000 μm) / total magnification