Investigatory Project in Physics
The Problem and its Background
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?
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.
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
The materials needed for this experiment are a laser, a flashlight, a knife, light-colored jelly and dark-colored jelly.
Preparing the jelly lenses
Mix up your jelly, but only use half as much water as normal. You...