Microscopy: magnification and resolution answer different questions
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| magnification/ˌmæɡnɪfɪˈkeɪʃn/ | 放大倍数 | fàng dà bèi shù |
| resolving power/rɪˈzɒlvɪŋ ˈpaʊə/ | 分辨能力 | fēn biàn néng lì |
What would explain this observation?
- Enlarging a blurred photograph gives a larger blur. A microscope must distinguish close structures as well as make the image larger.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Magnification 放大倍数 is image size divided by real size. Resolution is the ability to distinguish two close points as separate. Electron microscopes have much higher magnification and resolving power 分辨能力 than light microscopes, allowing finer cell structures to be investigated. This development increased biological understanding of sub-cellular detail.
- magnification: Image length divided by actual length; resolving power: Ability to distinguish close features as separate.
What improvement reveals two nearby structures as separate?
Choose the relation for the unknown: real size = image size/magnification, and image size = real size×magnification. Convert to the same length unit first. A stated scale bar continues to describe the particular image even if the displayed image is resized, provided the bar is resized with it.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Choose the relation for the unknown: real size = image size/magnification, and image size = real size×magnification. Convert to the same length unit first. A stated scale bar continues to describe the particular image even if the displayed image is resized, provided the bar is resized with it.
- Measure the image and its scale bar rather than assuming the screen magnification is a printed original value. Include units and use sensible precision. Compare a light and electron image for actual resolved detail; do not assume a darker or more colourful picture necessarily resolves more.
Which two habits make the investigation or model in this case more defensible?
Measure the image and its scale bar rather than assuming the screen magnification is a printed original value. Include units and use sensible precision. Compare a light and electron image for actual resolved detail; do not assume a darker or more colourful picture necessarily resolves more.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a structure measures 24 mm on an image magnified 6,000 times. Real size = 24/6,000 = 0.004 mm = 4 micrometres = 4×10⁻⁶ m. The division is valid because magnification is a dimensionless length ratio. Area would scale with the square of the length magnification.
A 12 mm image is magnified 3,000 times. Find real length in micrometres. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A 12 mm image is magnified 3,000 times. Find real length in micrometres.
The result is 4 μm. Known: a structure measures 24 mm on an image magnified 6,000 times. Real size = 24/6,000 = 0.004 mm = 4 micrometres = 4×10⁻⁶ m. The division is valid because magnification is a dimensionless length ratio. Area would scale with the square of the length magnification.
Check the conclusion and its limits
- Resolution and magnification are not synonyms. A larger screen image does not change the real cell size. Misusing millimetres and micrometres gives a thousandfold error even if the calculator division is otherwise correct.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Increasing the displayed size always improves resolution. This claim is false: Resolution and magnification are not synonyms. A larger screen image does not change the real cell size. Misusing millimetres and micrometres gives a thousandfold error even if the calculator division is otherwise correct.
Microscopy: magnification and resolution answer different questions: Choose the relation for the unknown: real size = image size/magnification, and image size = real size×magnification. Convert to the same length unit first. A stated scale bar continues to describe the particular image even if the displayed image is resized, provided the bar is resized with it.
Increasing the displayed size always improves resolution.
Resolution and magnification are not synonyms. A larger screen image does not change the real cell size. Misusing millimetres and micrometres gives a thousandfold error even if the calculator division is otherwise correct.
Image length divided by actual length: write the technical term.
magnification means Image length divided by actual length.