A biological microscope is a complex instrument, but understanding its key parts is essential for proper use:

l Eyepiece (Ocular): This is the lens you look through at the top of the microscope. It typically has a magnification power of 10x or 15x and projects the magnified image from the objective lens into your eye.

l Objective Lenses: These are multiple lenses mounted on a rotating nosepiece located below the stage. Each objective lens has a different magnification power, ranging from low power (4x or 10x) for a wider field of view to high power (40x or 100x) for magnified close-up views. You can switch between objective lenses to achieve the desired magnification.

l Stage: This is a flat platform where you place the slide containing the specimen you want to view. The stage has clips to hold the slide securely and knobs to move it horizontally and vertically for positioning under the objective lens.

l Illuminator: This is a light source, usually a lamp, located at the base of the microscope. It directs light upwards through the condenser lens and then through the specimen for better visibility.

l Condenser Lens: Located below the stage, this lens concentrates the light from the illuminator and focuses it onto the specimen. Some condenser lenses have an iris diaphragm to control the amount of light reaching the specimen.

l Focus Knobs: These knobs, coarse and fine adjustments, are used to raise or lower the stage, bringing the specimen into sharp focus at different magnifications.

l Diaphragm: This adjustable disc is located below the condenser lens and controls the cone of light that illuminates the specimen. Opening or closing the diaphragm allows you to adjust the brightness and contrast of the image.