Academic journal article The Science Teacher

Pinhole Microscope

Academic journal article The Science Teacher

Pinhole Microscope

Article excerpt

... adapted from TOPS Learning Systems


1. Hole-punch an index card. Cover the hole with a bit of aluminum foil. Use clear tape to hold it.


2. Press down hard on a pin into the center of this hole, while the card rests on a smooth hard surface. (With strong backlighting, you should see a distinct pin-prick.)


3. Stick the pin on a strip of clear tape and center it over the mouth of a small jar.

4. Hold the jar up to a very bright light (never the sun) with the foil against your eyelashes. Look at the pin through the pinhole.


5. Move the jar closer to your eye so the pin looks bigger, and bigger, and bigger, and bigger ...


To experience pinhole magnification.


Copy the activity above for each student or lab group.

Step 3-4. Tips for good, and safe, pinhole magnification:

Lighting--brighter is better. Plain light bulbs or bright sky are good. Never aim toward the sun. Avoid viewing toward halogen bulbs, which can expose the eyes to damagin UV radiation. Incandescent bulbs get hot enough to burn skin.

Pinhole Trade-offs--A big pinhole allows a wide, bright field of view. A tiny pinhole allows an astonishingly sharp focus at very close range. Bigger is easier. …

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