The Triangle Method:
I
A
×
M
- I = Image size (what you measure)
- A = Actual size (real size)
- M = Magnification
Key Formulas:
Magnification = Image Size ÷ Actual Size
Actual Size = Image Size ÷ Magnification
Image Size = Actual Size × Magnification
Worked Example:
Question: A cell appears 30mm long under ×400 magnification. What is its actual size?
Solution:
- Image size = 30 mm
- Magnification = ×400
- Actual size = Image size ÷ Magnification
- Actual size = 30 mm ÷ 400 = 0.075 mm
- Convert to micrometers: 0.075 mm × 1000 = 75 μm
This diagram covers Size Calculations within Microscopy for GCSE Biology. Light and electron microscopes, magnification and resolution calculations, specimen preparation, staining techniques, and practical microscopy skills It is section 6 of 20 in this topic. Focus on the labels, the relationships between parts, and the explanation that turns the diagram into an exam-ready answer.
Practice questions for Microscopy
What is magnification?
Explain why specimens are stained before viewing under a light microscope.
Quick recall flashcards
What is magnification?
Magnification is how many times larger an image appears compared to the actual object. It tells us how much bigger something looks through a microscope.
What is resolution?
Resolution is the ability to distinguish between two separate points that are close together. It determines how clear and detailed an image is.