Jelly Optics

Jelly Optics
Investigatory Project in Physics

Chapter 1
The Problem and its Background

Introduction

When light hits a boundary between two substances, it often bends. This is called refraction. Refraction is the bending of a wave when it enters a medium where its speed is different. The refraction of light when it passes from a fast medium to a slow medium bends the light ray toward the normal to the boundary between the two media. Refraction is responsible for image formation by lenses and the eye.

A. Statement of the Problem

Is jelly an effective substitute for lenses in studying refraction of light?

B. Hypothesis

If we would use jelly as a substitute for lenses, then we would be able to study the refraction of light.

C. Significance of the Study

The significance of our study is that, we would be studying about the refraction of light. We would make use of jelly as a substitute for lenses so we could understand the function of lenses better. Our investigatory project would help us understand more about Optics.

D. Scope and Limitations

Our study is all about optics but it focuses on the refraction of light. We would be basing our study on the jelly which we would use as our lenses. We do not know if using another alternative as lenses would yield the same result as that of the jelly. This would be beneficial for students because we will make use of simple substitute materials which could be found at home.

Chapter 2
Review of Related Literature The Role of Light to Sight
The bottom line is: without light, there would be no sight. The visual ability of humans and other animals is the result of the complex interaction of light, eyes and brain. We are able to see because light from an object can move through space and reach our eyes. Once light reaches our eyes, signals are sent to our brain, and our brain deciphers the information in order to detect the appearance, location and movement of the objects we are sighting at. The whole process, as complex as it is, would not be possible if it were not for the presence of light. Without light, there would be no sight.
The objects that we see can be placed into one of two categories: luminous objects and illuminated objects. Luminous objects are objects that generate their own light. Illuminated objects are objects that are capable of reflecting light to our eyes.

Refraction of Light

Refraction of Light as it passes from less dense to more dense mediums
When light passes from a less dense to a more dense substance, (for example passing from air into water), the light is refracted (or bent) towards the normal. | The normal is a line perpendicular (forming a 90 degree angle) to the boundary between the two substances. The bending occurs because light travels more slowly in a denser medium. |

A demonstration of refraction can be conducted at home in a dark room. All that is needed is a flashlight, a clear glass filled with water and a small mirror.

Figure adapted from Ahrens, 1994 * Figure (a): No bending of light occurs and it simply passes directly into the water undisturbed, leaving only a straight beam of light all the way to the bottom of the glass. * Figure (b): As the light enters the water, it is refracted. Since the light is passing from air (less dense) into water (denser), it is bent towards the normal. The beam of light would appear to bend at the surface of the water. * Figure (c): The light would leave the flashlight, bend at the surface of the water, reflect off the mirror at the bottom of the glass and move towards the surface, where it would bend outward at the same angle it bent in on the way in.
Lenses

Chapter 3
Methodology

A. Materials The materials needed for this experiment are a laser, a flashlight, a knife, light-colored jelly and dark-colored jelly.

B. Procedure
Preparing the jelly lenses
Mix up your jelly, but only use half as much water as normal. You need to make very stiff jelly. Pour the jelly into your mold and leave it to set overnight. When the jelly has set, tip it out onto the cutting board. Use the knife to cut the jelly into the shape of some lenses such as:

1. wide in the middle and thin at the ends 2. thin in the middle and wide at the ends

Studying light with the use of jelly lenses

First, shine light from the laser through the jelly lenses and look at how they bend the light. Next, shine light from the flashlight through the jelly lenses and look at how they bend the light. Record your findings, comparisons and observations.

C. Findings
When light goes from air into the jelly, it bends away from the surface of the jelly. When it goes from jelly into the air, it bends towards the surface of the jelly. When the jelly surface is curved, rays of light hitting at different spots on the surface will either spread out or move together.

Type of Lens | Result | Concave Lens(thick on the ends, thin in the middle) | The rays of light were spread out. (Diverged) | Convex Lens(thin on the ends, thick in the middle) | The rays of light bent towards each other, until they cross over and then spread out again. (Converged) |

The strength of a lens depends on its shape and the material it is made from. Different materials will bend light by different amounts. The laser was able to pass through the light-colored jelly because it is lighter in color and transparent. The laser was not able to pass through the dark-colored jelly because it is made of colloidal properties and it is translucent because of its dark color. Based from our experimentation, we observed that the refraction of light is different depending on the object it passes through. As light enters the jelly, the change in medium causes a change in speed.

Chapter 4

Conclusion

We therefore conclude that making use of jelly as a substitute for lenses is possible in order to study the refraction of light. Light can pass through some materials but not others. When light hits an object that it cannot pass through, it forms a shadow. If light passes through an object easily, it is a transparent object. A translucent object lets some light through but an opaque object lets no light through. Through this simple experiment, we made use of jelly as a substitute for lenses. We were able to see that light travels differently depending on the object it passes through. We were able to fully understand the refraction of light as it passes through different media.

Recommendation

We made our investigatory project to be able to study about refraction of light. We made jelly as a substitute for lenses and made use of a flashlight and a laser as a source of light. Further study and experimentation can be done regarding this topic. Other objects could be used as substitutes for lenses and light source.

Bibliography: http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/refr.html http://www.csiro.au/resources/jelly-lens-activity.html http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/opt/mch/refr/less.rxml http://www.physicsclassroom.com/class/refln/u13l1a.cfm http://en.wikipedia.org/wiki/Optical_physics
http://www.howstuffworks.com/light.html

Bibliography: http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/refr.html http://www.csiro.au/resources/jelly-lens-activity.html http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/opt/mch/refr/less.rxml http://www.physicsclassroom.com/class/refln/u13l1a.cfm http://en.wikipedia.org/wiki/Optical_physics http://www.howstuffworks.com/light.html