The eyepiece lens of a microscope can be fitted with an eyepiece graticule.
Which of these statements about eyepiece graticules are correct?
1) They measure the actual length of cells in micrometres.
2) They help biologists to draw cells with correct proportions.
3) They change in size when the objective lens is changed from ×10 to ×40.
1 )
1, 2 and 3
2 )
1 and 3 only
3 )
1 only
2 only
