Final answer:
The usual thickness of a paraffin section used in microscopy is typically around 0.75 to 5 micrometers.
Step-by-step explanation:
The usual thickness of a paraffin section used in microscopy is typically around 0.75 to 5 micrometers (µm). Standard light microscopy usually requires sections of about 5 µm thickness, while electron microscopy may require much thinner sections, often around 0.75 µm. The preparation process involves embedding the biological material in paraffin wax, followed by sectioning with a microtome to ensure thin, uniform slices that are suitable for examining under a microscope. The thickness is carefully controlled since it affects the resolution and the quality of the microscopy images.