A complete, exam-ready breakdown.
The microscope is an instrument used to produce a magnified image of tiny objects so they can be studied in detail. Biology students use it to observe cells, tissues, and microorganisms.
Microscopes are mainly divided into:
Light Microscope (Common in schools)
Electron Microscope (Advanced, not used in secondary schools)
Below is the standard light microscope structure and each function:
The lens you look through at the top.
Usually magnifies ×10 or ×15.
First point of magnification.
Holds the eyepiece and objective lenses at correct distances.
Ensures light travels properly from object to your eye.
Rotating part that carries the objective lenses.
Allows you switch magnification levels easily.
Main magnifying lenses.
Usually ×4 (scanning), ×10 (low power), ×40 (high power), sometimes ×100 (oil immersion).
Provide different levels of detail.
The flat platform where the slide is placed.
Has clips to hold the slide in position.
Secure the slide to prevent movement while viewing.
Located under the stage.
Focuses and concentrates light onto the specimen for a clearer image.
Adjusts the amount of light reaching the object.
Helps improve contrast and clarity.
Moves the body tube/stage up and down quickly.
Used for general focusing on low power.
Never use this on high power — you can break the slide.
Makes slow, precise focusing movements.
Used on high power for sharp, detailed images.
Provides or reflects light upward through the condenser and specimen.
Older microscopes use mirrors; modern ones have built-in bulbs.
Supports the upper parts of the microscope.
Used to carry the microscope safely.
Bottom support of the microscope.
Stabilizes the whole instrument.
Slide: Holds the specimen being viewed.
Cover slip: Thin glass placed over the specimen to flatten it and protect the lens.
Multiply eyepiece magnification × objective lens.
Example:
Eyepiece: ×10
Objective: ×40
Total: 10 × 40 = ×400
Always begin focusing with low power.
Adjust the diaphragm for the best contrast.
Carry a microscope using the arm + base.
Use fine adjustment only on high power.
Know the functions, not just the names — WAEC/JAMB love to test that.