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A reflection on the uses of a pencil an everyday object

As you look at Mary in class, you are able to see Mary because she is illuminated with light and that light reflects off of her and travels to your eye. In the process of viewing Mary, you are directing your sight along a line in the direction of Mary.

If you wish to view the top of Mary's head, then you direct your sight along a line towards the top of her head. If you wish to view Mary's feet, then you direct your sight along a line towards Mary's feet.

And if you wish to view the image of Mary in a mirror, then you must direct your sight along a line towards the location of Mary's image. This directing of our sight in a specific direction is sometimes referred to as the line of sight. The Broken Pencil As light travels through a given medium, it travels in a straight line.

However, when light passes from one medium into a second medium, the light path bends. The refraction occurs only at the boundary.

  1. As a result, the image of the pencil appears to be broken. Science, Imagination, and the Illustration of Knowledge, Oxford 2013 November for feedback on earlier iterations of this work.
  2. Everyday uses of minerals download these and more for free at what tools can you use instead of a pencil pick any object and discover the origin of the materials from which it is materials used to make a pencil are mined and which are grown this can be a cooperative group.
  3. Unfortunately this graphite loaded, eraser-tipped writing spear has become an alienated object as i readily admit my dependence on a new technology of writing an ode to a user friendly pencil or any similar topic specifically for you do not waste everyday use by alice walker.

Once the light has crossed the boundary between the two media, it continues to travel in a straight line. Only now, the direction of that line is different than it was in the former medium.

If when sighting at an object, light from that object changes media on the way to your eye, a visual distortion is likely to occur. This visual distortion is witnessed if you look at a pencil submerged in a glass half-filled with water.

A reflection on the uses of a pencil an everyday object

As you sight through the side of the glass at the portion of the pencil located above the water's surface, light travels directly from the pencil to your eye. Since this light does not change medium, it will not refract. Actually, there is a change of medium from air to glass and back into air.

Because the glass is so thin and because the light starts and finished in air, the refraction into and out of the glass causes little deviation in the light's original direction.

As you sight at the portion of the pencil that was submerged in the water, light travels from water to air or from water to glass to air. This light ray changes medium and subsequently undergoes refraction.

As a result, the image of the pencil appears to be broken. Furthermore, the portion of the pencil that is submerged in water appears to be wider than the portion of the pencil that is not submerged. A reflection on the uses of a pencil an everyday object visual distortions are explained by the refraction of light. In this case, the light rays that undergo a deviation from their original path are those that travel from the submerged portion of the pencil, through the water, across the boundary, into the air, and ultimately to the eye.

At the boundary, this ray refracts. The eye-brain interaction cannot account for the refraction of light. As was emphasized in Unit 13, the brain judges the image location to be the location where light rays appear to originate from.

This image location is the location where either reflected or refracted rays intersect. The eye and brain assume that light travels in a straight line and then extends all incoming rays of light backwards until they intersect. Light rays from the submerged portion of the pencil will intersect in a different location than light rays from the portion of the pencil that extends above the surface of the water.

Refraction and Sight

For this reason, the submerged portion of the pencil appears to be in a different location than the portion of the pencil that extends above the water. The diagram at the right shows a God's-eye view of the light path from the submerged portion of the pencil to each of your two eyes. Only the left and right extremities edges of the pencil are considered. The blue lines depict the path of light to your right eye and the red lines depict the path of light to your left eye.

Observe that the light path has bent at the boundary. Dashed lines represent the extensions of the lines of sight backwards into the water. Observe that these extension lines intersect at a given point; the point represents the image of the left and the right edge of the pencil. Finally, observe that the image of the pencil is wider than the actual pencil.

A ray model of light that considers the refraction of light at boundaries adequately explains the broken pencil observations. Flickr Physics Photo A straw is placed with a diagonal orientation within a half-filled beaker of water. At the surface of the water, the straw appears to be misaligned or broken; the portion of the straw above the water is shifted relative to the image viewed under the water. The bending of the path of light as it passes from the water to air causes the observed distortion of the image of the straw.

  1. As was emphasized in Unit 13, the brain judges the image location to be the location where light rays appear to originate from. Subsequently, the hunter launches the spear at the location where the fish is thought to be and misses the fish.
  2. Observe that these extension lines intersect at a given point; the point represents the image of the left and the right edge of the pencil. Sometimes you need a capacitive stylus but really don't want to buy an expensive one diy capacitive stylus everyday objects can be used as a stylus for capacitive touch screens like the ones found in smart phones and a pencil or pen wrapped in foil is probably the simplest example.
  3. There is scarcely any object in our everyday world, both natural and synthetic object symmetry element s and explanation refrigerator front door to your home automobile starfish barbells pencil tree slice of bread coat hanger blue jeans uncooked egg compact disc open. Reflection in use - the periscope a periscope is an optical instrument used predominantly in submarines so that the submarine crew can see what is happening above the surface of water without having to surface the animation below describes how a periscope works.

The broken pencil phenomenon occurs during your everyday spearfishing outing. Fortunately for the fish, light refracts as it travels from the fish in the water to the eyes of the hunter.

1. Child Drawings

The refraction occurs at the water-air boundary. Due to this bending of the path of light, a fish appears to be at a location where it isn't. A visual distortion occurs.

Subsequently, the hunter launches the spear at the location where the fish is thought to be and misses the fish. Of course, the fish are never concerned about such hunters; they know that light refracts at the boundary and that the location where the hunter is sighting is not the same location as the actual fish.

How did the fish get so smart and learn all this? They live in schools. We will investigate this aspect of refraction in great detail in Lesson 2. For now, it is sufficient to say that as the hunter with the spear sights more perpendicular to the water, the amount of refraction decreases.

The most successful hunters are those who sight perpendicular to the water. And the smartest fish are those who head for the deep when they spot hunters who sight in this direction. Since refraction of light occurs when it crosses the boundary, visual distortions often occur. These distortions occur when light changes medium as it travels from the object to our eyes.

What seems like a lot of root beer is actually a lot of glass. The deception is uncovered when the root beer mug is submerged in water.

When looking at the mug above the water level, there appears to be a lot of root beer. But when looking at the mug below the water level, one observes the truth; the water surrounding the glass minimizes the effect of refraction and reveals the large quantity of glass.