The Microscope

Learning Objectives By the end of this topic, you will be able to: Name the parts of the microscope and their functions. Use the microscope to observe biological specimens Know the difference between the light microscope and the electron microscope

Compound Microscopes The microscopes used in our lab are called compound microscopes because they have two magnifying lens a. The Eyepiece Lens is the lens that you look through. b. The objective lens is the lens that is immediately above the specimen.

The Objective Lenses There are three objective lenses: - the scanning lens with the 4X label - the low power lens with the 10X label - the high power lens with the 40X label

Parts of the Microscope

Parts of the Microscope Function Lenses Magnification Stage To place the slide on Clips Hold the slide in place Diaphragm To control the amount of light Coarse Focus Knob To focus the image Fine Focus Knob To precisely focus the image Light To supply light to the object

Learning Check Label the parts of the Microscope

Magnification Magnification = the magnifying power of the eyepiece lens x the magnifying power of the objective lens. Example: Eyepiece lens = 10X Objective lens = 4X Total magnification = 10 x 4= 40X

Focussing The Image The course focus knob allows for dramatic or large movement of the objective lens. The fine focus knob allows for very slight movement of the objective lens.

The Stage and the Diaphragm The stage has two metal clips to hold the microscope slide in place. The diaphragm allows light to be focused onto the specimen through a hole in the stage.

ELECTRON MICROSCOPE

Electron Microscope Uses Electrons instead of light Electrons have much lower wavelength than light Resolution is much better Magnification is much greater

Images from Electron Microscope Platelet Bacteria Cytplasm

Learning Check What is the function of each of these parts of the Microscope? Eyepiece Lens Objective Lens Stage Clips Diaphragm Coarse Focus Knob Fine focus Knob Light

What have you learned? Can you? Name the parts of the microscope and their functions. Use the microscope to observe biological specimens Outline the differences between the light microscope and the electron microscope