Microscopy: Development of Practical Skills in Biology: Biology OCR A Level

What is the function of a stage micrometer?

To calibrate an eyepiece graticule so that it can be used to make measurements.

How is an eyepiece graticule calibrated?

Select the desired magnification and objective. Place the stage micrometer on the stage.

Line up the scales of the micrometer and the eyepiece graticule.

Count the number of divisions on the eyepiece graticule equivalent to each division on the stage micrometre.

Calculate the length of one division of the eyepiece graticule.

Outline the procedure to preparing a slide.

Stain the sample with an appropriate dye.

Mount the sample on the slide.

Place a cover slip carefully on the slide, avoiding air bubbles.

How is magnification calculated?

Magnification = Size of image / Size of object