Microscopy

This lesson covers the principles and techniques of microscopy as required by the Edexcel GCSE Biology specification (1BI0), Topic 1: Key Concepts in Biology. You need to understand the differences between light and electron microscopes, be able to use the magnification formula, perform unit conversions, and describe Core Practical 1 — using a light microscope to observe cells.

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Why Do We Need Microscopes?

Most cells are too small to be seen with the naked eye. Microscopes are instruments that produce a magnified image of a small object, allowing us to observe structures that would otherwise be invisible.

Two key terms you must understand:

• Magnification — how much larger the image is compared to the actual size of the object. It is a ratio and has no units.
• Resolution — the ability to distinguish between two separate points that are close together. Higher resolution means you can see finer detail.

Exam Tip: Magnification and resolution are different things. A microscope can have high magnification but poor resolution, meaning the image is large but blurry. Resolution determines the level of detail you can see.

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Light Microscopes