Key concepts
Lens
Magnifying glass
Eyes
Calorie-free

Introduction
Accept you lot ever studied an everyday object through a magnifying drinking glass—and been amazed at what you could see? Or have y'all ever noticed, for example in a swimming pool, that an object that is sticking out of the water looks different simply above and just below the surface? In this activity yous will learn a petty flake more about both of these observations. Get gear up to curve light, magnify letters and accept fun with water drops—all while getting a glimpse into how lenses work!

Lenses are the key components in eyeglasses, contact lenses, binoculars and telescopes—just to name a few devices. With this action a homemade magnifying glass is only a drop away!

Background
You see an object considering light rays reflected from the object shine into your eye, creating an image on the retina inside your centre. Signals to your brain allow it to re-create the picture of the object.

A calorie-free ray bouncing off an object usually travels in a straight line to your heart. Things change when a transparent material, such every bit glass or water, gets in the way. When a light ray traveling through air enters such a fabric, it changes direction, creating a sort of kink. Another kink is introduced when the ray leaves the material. Therefore, the final image of the object in your center might be unlike due to the changes in direction of the light on its style to your centre. Your encephalon is unaware of these kinks and expects an image created by rays that traveled in a straight line. As a event, information technology might reconstruct a picture that is different from the initial object. Your eyes and brain might have been fooled!

Lenses use these kinks to brand objects expect bigger or smaller, closer or further away. A convex lens bends lite rays inward, which results in the object beingness perceived equally larger or closer. A concave lens bends rays outward; you go the perception that objects are smaller or farther away. There is no overall bending of lite for a flat lens. You perceive the object every bit it is.

At present that you know a fiddling about light and lenses, are y'all ready to let your optics and encephalon be fooled?

Materials

  • A paper folio
  • Ii rulers with metric measurements on them, preferably with dark markings
  • One transparency film or clear canvass protector
  • Drinking glass with water
  • Medicine dropper (optional)
  • Mobile device with a camera (optional)
  • Small transparent plastic cup or tiny tasting cup with a flat bottom (optional)

Preparation

  • Find a waterproof piece of work expanse.
  • Select an article in the newspaper with a small-scale font. Y'all can utilize your ruler to measure the height of the letters; they should be a few millimeters high.

Process

  • Place the transparency film on top of a newspaper folio.
  • Create a drop of water almost the middle of the transparency picture. Utilize a water dropper or your finger to let two or three drops fall on the film and merge into one bigger drop. Examine your water drib. Is the top of the drib surface apartment, curved inward or curved outward?
  • Shift your transparency film so the water drop lays on top of the small print letters.
  • Close or cover one eye and look from above with the other heart at the letters under the drop. Compare them with the letters side by side to simply not covered by the drop. Do they wait the aforementioned? Does one appear bigger or smaller than the other?
  • Using two hands, carefully lift and concord the transparency flick about one-half an inch higher up the paper, leaving the newspaper on your piece of work surface. You might need assistance lifting the transparency film if y'all like to encompass i centre with a hand.
  • Close or comprehend one center and look advisedly from to a higher place through the water driblet at the messages on the paper. Do the messages announced different than when the transparency film rested on the newspaper? What happens when you move the transparency film farther up?
  • Motility the transparency flick up and downwards a couple of times looking from to a higher place through the water drop with i center. How does your perception of the letters change every bit y'all move the transparency picture show farther upward or back downwards? Why practise you call back this happens?
  • To measure out the magnification factor of your water drib, put a ruler under your transparency movie on your work surface and some other ruler next to the drop on top of the transparency film, merely exist certain to prevent the ruler from touching the drop.
  • Lift the transparency moving picture with the tiptop ruler and water driblet about 1.iii centimeters upward and exercise your all-time to measure the length of a millimeter indication of the bottom ruler, as seen through the water driblet. (Yous might need help lifting the transparency film together with the ruler and the h2o driblet.) How many millimeters does one millimeter indication measure out? This number tells you lot by what factor objects announced bigger when seen through your water driblet. Are you surprised about the magnification gene y'all obtained?
  • Measure the magnification gene of your h2o drop when you lift the transparency film college up. Does the magnification factor change when you lift the transparency college? Could yous find ways to make the magnification factor very large?
  • Echo the activity, this time using a larger water drop. What happens to the curvature of the elevation surface of the water drop when you increase the size of the drop? Is it more, less or similarly curved? Practise bigger water drops yield a dissimilar magnification factor?
  • Extra: What practice yous recall would be the optimum water drop size and its pinnacle above the newspaper to increase the readability of your chosen paper line? Would yous choose the same atmospheric condition if yous were investigating the details of an insect?
  • Extra: Go around the house or the garden looking at objects through your new magnification drinking glass. What kind of surprising details can you lot discover?
  • Extra: Y'all but used water to create a magnifying glass, making objects appear larger. What do you think will happen if you look through a bigger layer of water held in a cup? To test this, find a minor or tiny transparent plastic cup with a flat bottom. To verify that the loving cup itself does not act as a lens, place the empty cup over a direct line found in your newspaper, look through the cup and observe. Does the line appear direct? Does it appear to accept the aforementioned thickness if you lift the cup? If not, notice another cup, because the bottom of this cup already acts as a lens. Why practice y'all call up it is of import that the cup used to exam if a layer of h2o in a cup acts as a lens does non act equally a lens already? Once you have a cup that does not act like a lens, make full it with a layer of water (about 1.3 centimeters high) and wait from higher up through the water to the letters on your paper. How do the letters appear? Does their appearance change when you move the cup up and down? You might want to shift to a font with larger letters. Can you calculate the magnification gene of this lens? Notation that a magnification factor smaller than 1 indicates the object appears smaller than information technology is. As an example, a magnification factor of one half indicates that the object appears to be one-half its size.
  • Extra: Optical instruments often use a combination of several lenses. If you fabricated both the h2o-drib lens and the cup-with-h2o lens, find what happens if you combine both. Yous can put the transparency on top of your cup and expect from above or ask a helper to agree your transparency pic with the h2o drop as you hold the loving cup in a higher place information technology. What practice you think will happen? Tin you measure the magnification factors for both lenses individually (at the exact distance y'all are holding them when you combine both) and when combined? If yous practice this for a couple of different distances, you might be able to develop a formula.
  • Actress: Would other liquids also create magnification? Would one liquid work better than another? Think of oil or vinegar or soy sauce. Which ones do you think might work, and why?


Observations and results
Did you see how objects appear larger when looked at through a water drib? The surface of a water drop curves outward to make a dome. This outward, or convex, curvature bends calorie-free rays inwards. The consequence is an enlarged image on the retina of your eye. The object appears bigger than it is.

The surface of a smaller drop is even more than curved, creating a bigger change in management of the light ray. The consequence is a larger magnification. Changing the position of the h2o drop with respect to the letters and your center will as well affect the magnification factor. Due to something called the capillary effect, still, a layer of h2o in a cup shows a surface that is slightly bent in. It will act every bit a concave lens that bends the calorie-free rays outward. As a event, letters seen through the layer of water in a cup announced smaller than they are. When yous combine several lenses, the magnification cistron of the set of lenses is the product of the magnification factors of the private lenses.

Any articulate liquid volition work as a lens. Equally long every bit the bottom and acme surfaces of the layer or drop are not parallel, the lens will change the appearance of the object. Depending on the liquid, the magnification factor of similar drops fabricated upwardly of different liquids volition vary.

More than to explore
Simple Magnification, from The Florida State University
A Magnifying Discovery, from Scientific discipline Buddies
Picture This: Building a Cell Phone Microscope, from Science Buddies
Measure Surface Tension with a Penny, from Scientific American

This activity brought to you in partnership with Science Buddies

Science Buddies