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=**Water Droplets as Convex Lenses**=

HOW IT WORKS
Water becomes spherical droplets due to its surface tension. Because of its transparency, theis sphere shape wokrs as a convex lens that can be used to magnify objects.

When light from an object travels through the lens like in the diagram below, when the light enters the water it does not travel as fast as it does in air. This causes the light to bend as the speed of light in the medium changes. The trick to convex lenses is where the light exits the lens. Because it is rounded, the rays of light on the outside exit the water sooner than the rays towards the center and therefore they are refracted at a different angle depending on their placement. This is where the focal point comes in. Magnifiers often blur things unless you have them in the exact right position in regards to your eye. When the focal point where all the rays have been refracted towards is lined up perfectly with the retina in the back of your eye, you can see the object clearly. Like most things in physics, things also work the other way. If a light is shone on a convex lens, then the rays will become a straight beam of light rather than an arc of light. Glasses for farsighted people are examples of convex lenses. They change the normal focal point so that it is in front of the retina instead of farther back.

In this photo, the pixels of the screen are magnified and the text is bent in the same shape as the water droplet.



FLIPPED IMAGES
If the object is far away enough from the magnifier, it will result in a flipped image. This flipped image will also contain much more of the image, but on a smaller scale. This is like lbeing the image that we were magnifying before. It is upside down because the rays have traveled past the focal point at their same angle, causing the rays to end up on opposite sides of the normal ray.

HISTORY
The oldest known lens is called the Nimrud Lens. It was found in what is now Iraq and it is from the 5th Century BC, placing its origin with the ancient Assyrians. This is one explanation as to how they knew so much about astrology. It is also possible that they were inspired to make this lens by observing water droplets and the magnifying effects they have. From then on, lenses have been improving and recurring throughout many civilizations. Convex lenses that were almost perfectly elliptical were found at a known Viking site and the Ancient Greeks wrote about lenses in their literature. Lenses have also been found in ancient civilizations such as Egypt, Babylon, and Rome.

TECHNOLOGY
More recently, lenses have been used often in the making of new technology. in 1303, Bernard of Gordon mentioned the use of lenses as spectacles to correct far-sightedness. The microscope was invented in 1590 using both converging and diverging lenses by Zacharius Jensen. Hans Lippershev, a Dutch spectacle-maker, invented the telescope using lenses in 1608. Lenses have been critical in creating many types of devices to aid in seeing.

SOCIETAL IMPACT
Without the discovery of lenses, our society would be very different. Observations of our universe using telescopes allowed us to realize that the Earth was not the center of the universe and that planets orbit around the sun. On the opposite side, microscopes let us see thing on a tiny level, which has led to tons of discoveries about diseases, bacteria, and all life. Without that knowledge there would not be reliable cures and the human race probably would have died out long ago. An understanding of lenses has also allowed for the invention of glasses, which help many people get through their lives and maximize their potential. Lenses have taken a long journey, and the inspiration from nature- the water droplet- is what has led it along the way.

Sources: http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/simmag.html http://www.education.com/study-help/article/physics-help-lenses-mirrors/ http://www.optics1.com/optics_history.php http://www.ancient-wisdom.co.uk/optics.htm Photos: http://www.photographyblogger.net/18-refreshing-water-droplet-photos/ http://fphoto.photoshelter.com/image/I0000ZF6DdtrXzcw http://fphoto.photoshelter.com/image/I0000o.GVzVp5SlQ

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