A pinhole in an index card can act like a magnifying glass, helping your eyes to focus on a very tiny object that is close to you. Unfortunately the tiny hole limits the amount of light that reaches your eye from the object, so the pinhole magnifier also makes the object appear less bright. You can make your own handy magnifier when you don’t have a regular one available with this simple experiment in science:
Topics covered
Magnification, Diopter, Retina
What will I need?
PIECE OF WHITE CARDBOARD
ALUMINIUM FOIL
STICKY TAPE
PIN / NEEDLE
SCISSORS
FLASHLIGHT (OPTIONAL)
Procedure (Method)
Unfortunately, this section is only available in the e-book version of the project.
How does it work?
Unfortunately, this section is only available in the e-book version of the project.
In this science experiment, the pinhole magnifier works simply because the closer you get to an object, the bigger it looks to you. Objects that are closer to you form a larger image of the object on your retina. There is however a limit to this, because when you get too close to the object, your eye is not able to bend some of the light rays enough to obtain a focused image, and hence the image becomes blurred.
The pinhole magnifier prevents this problem by limiting the rays that can reach you from each part of the object. There is, however, a trade-off between the sharpness of the image and its brightness. A tiny pinhole produces a very sharp image, but because it cuts down on the number of rays that enter your eye, the pinhole makes the object look much less bright and you may need additional lighting to view the object.
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