Magnifying glasses are just converging lenses in a convenient holder.
Converging lenses are pieces of glass shaped so that they focus light into a point. Converging lenses typically bulge out in the center and have tapered edges. Scientists have long used the focusing properties of the converging lens to create telescopes, glasses and televisions. Converging lenses have a "focal point," the point where they direct light. Determining the focal point will aid you in using the converging lens as a magnifying lens or for other purposes.
Instructions
1. Take the converging lens and the pen and hold them in one hand each.
2. Hold the lens in the middle of the line of sight between you and your pen tip, so that the lens is between you and the pen. Make sure you can see the tip of the pen through the lens.
3. Bring the pen tip closer and farther from the lens. Notice how at some point the pen will be "reversed," and the closer you bring it to the lens, it will right itself.
4. Find the point between where the pen is "reversed" and "correct," and you cannot see the tip of the pen. This in-between spot is the focal point. Anything between the lens and the focal point will be magnified right-side up, and anything on the other side of the focal point from the lens will be magnified in reverse.
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