Distinguish magnification from resolution
Magnification enlarges an image; resolution determines whether two nearby points can be distinguished as separate.
Section 1.1 · The microscope in cell studies
AS Level · Cambridge International Biology 9700, 2028–2030. Written practice is self-checked; supervised practical skills and human subject-teacher review remain necessary.
Before you begin
- Know that cells are the basic units of living organisms and that a light microscope uses lenses to form an enlarged image.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What does resolution describe?
What you will learn
- Define magnification and resolution and explain how they differ
- Compare light and electron microscopy in relation to resolving detail
Enlargement is not the same as detail
Magnification is the number of times an image is larger than the actual object. Resolution is the ability to distinguish two close points as separate. Increasing magnification can make an image larger without revealing additional detail if the resolving power has not improved.
A useful microscope image needs both sufficient magnification and resolution. A large blurred image is not evidence that two nearby structures have been resolved.
Relate resolution to microscope type
Light and electron microscopes use different sources to form images. Electron microscopes can achieve higher resolution than light microscopes, allowing finer details to be distinguished. This comparison is about resolving detail, not simply how large an image appears.
When interpreting an image, distinguish what is resolved from what is merely enlarged. Do not assume that every feature is visible in every image or that increased magnification always improves resolution.
Pause and explain
What can happen when a blurred image is enlarged without improving resolution?
Worked example
A student enlarges a low-resolution image on a screen. It becomes bigger but two adjacent dots still look joined. Explain why.
Show the worked solution
- Enlarging changes displayed size.
- Resolution concerns whether nearby points appear separate.
Answer The display magnification increased, but the image resolution did not improve enough to distinguish the two dots, so they still appear joined.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Define magnification and resolution.
Give me a hint
Contrast enlargement with resolving two points.
Compare my reasoning
- Magnification compares image size with actual size.
- Resolution is the ability to distinguish close points separately.
Magnification is the number of times an image is larger than the actual object. Resolution is the ability to distinguish two close points as separate.
Look for these in your work
- Both definitions accurate
- Concepts distinguished
A photomicrograph is enlarged four times on a screen, but no new structures become visible. Explain the result.
Give me a hint
Separate displayed size from resolving power.
Compare my reasoning
- The display enlargement increases apparent image size.
- Resolution remains limited by the original image.
The image appears larger, but enlarging it does not restore detail that was not resolved in the original image.
Look for these in your work
- Magnification effect stated
- Resolution limitation stated
Which microscope type generally resolves finer detail, light or electron microscopy, and which property are you comparing?
Give me a hint
Name resolution rather than image size.
Compare my reasoning
- Electron microscopy can achieve higher resolution.
- Resolution is the ability to distinguish nearby points.
Electron microscopy can achieve higher resolution than light microscopy. The comparison concerns the ability to distinguish fine detail, not just image enlargement.
Look for these in your work
- Microscope comparison correct
- Property identified
Common mistakes
- Defining resolution as image enlargement
- Assuming a bigger image always contains more detail
- Confusing a higher-resolution image with a larger actual specimen
What can you explain now?
What does resolution describe?
Compare with the explanation
The ability to distinguish two close points as separate
This is the definition of resolving detail.
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Make it stick
How do magnification and resolution differ, and which microscope type generally resolves finer detail?
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