Cell Structure Quiz (5) Biology AS Level

The eyepiece of a microscope is fitted with an eyepiece graticule and a stage micrometer scale is placed on the microscope.
Which statements about the stage micrometer scale are correct?
1) The scale can be used to measure the actual length of cells directly.
2) The scale allows you to calibrate the eyepiece graticule.
3) Less of the scale is visible as the objective lens changes from ×10 to ×40.