INTRODUCTION

A mirror is an object that reflects light or sound in a way that preserves much of its original quality prior to its contact with the mirror. Some mirrors also filter out some wavelengths, while preserving other wavelengths in the reflection. This is different from other light-reflecting objects that do not preserve much of the original wave signal other than color and diffuse reflected light. The most familiar type of mirror is the plane mirror, which has a flat surface. Curved mirrors are also used, to produce magnified or diminished images or focus light or simply distort the reflected image (“Mungan,” 1999). Geometrical optics, or ray optics, describes light propagation in terms of "rays". The "ray" in geometric optics is an abstraction, or "instrument", which can be used to approximately model how light will propagate. Geometrical optics provides rules, which may depend on the color (wavelength) of the ray, for propagating these rays through an optical system. This is a significant simplification of optics that fails to account for optical effects such as diffraction and interference. It is an excellent approximation, however, when the wavelength is very small compared with the size of structures with which the light interacts (“Hecht,” 1987). Glossy surfaces such as mirrors reflect light in a simple, predictable way. This allows for production of reflected images that can be associated with an actual (real) or extrapolated (virtual) location in space. With such surfaces, the direction of the reflected ray is determined by the angle the incident ray makes with the surface normal, a line perpendicular to the surface at the point where the ray hits. The incident and reflected rays lie in a single plane, and the angle between the reflected ray and the surface normal is the same as that between the incident ray and the normal. This is known as the Law of Reflection. For flat mirrors, the law of reflection implies that images of objects are upright and the same distance behind the mirror as the objects are in front of the mirror. The image size is the same as the object size. (The magnification of a flat mirror is equal to one.) The law also implies that mirror images are parity inverted, which is perceived as a left-right inversion (“Moreno,” 2010). Mirrors are very useful in many ways. This project will be conducted to show another way of using mirrors. There are also many projects that use mirrors to show infinity but this study will be different and more interactive because the proponents will use different backgrounds that will let the audience have a tour to different places inside a room full of mirrors. The proponents will use LED lights that will be put around the mirror. The size of the room will be 6’ x 2’ x 2’ so one person at a time can enter. The background will be placed at the bottom of the room and it can be changed depending on the place the audience wants to enter. Different colors of lights will also be used to add effects in the mirror world. The project shows an application of Geometric Optics (a branch of Physics) through the reflection and refraction of light on the mirrors. It will portray infinity by using mirrors positioned in every side of the room with the addition of different colors of lights and backgrounds. It is interactive by letting a person go inside a 6’ x 2’ x 2’ room to experience a different world inside the mirror world.

STATEMENT OF THE PROBLEM

The main problem of the study is to determine the effects of different colors of lights and backgrounds on the reflection of the mirror. This project will also be conducted to: 1. Know if the effects of the different colors of lights would match the backgrounds on the reflection of the mirror. 2. Know the effect on the reflection if there are different backgrounds affecting on it.

OBJECTIVES

The main objective of the study is to add knowledge about Geometric Optics and its implications. This study also aims to: 1. Be more interactive with the use of larger space where a person can enter. 2. Let the audience see different places by using different colors of lights and backgrounds.

HYPOTHESIS

This study will use alternative hypothesis to agree or disagree to the following statements: 1. There is an effect on the reflection if there are different lights affecting on it. 2. There is an effect on the reflection if there are different backgrounds affecting on it.

DEFINITION OF TERMS

1. Incident Ray - ray of light approaching the mirror. 2. Reflected Ray - ray of light that leaves the mirror.

3. Normal Line - line can be drawn perpendicular to the surface of the mirror.

4. Angle of Incidence - angle between the incident ray and the normal.

5. Angle of Reflection - angle between the reflected ray and the normal.

6. Virtual image - image formed in this manner by extending back the reflected diverging rays.

7. Center of Curvature (C) – a curve is found at a point that is at a distance equal to the radius of curvature lying on the normal vector.

8. Focal Point (F) - the point at which initially collimated rays of light meet after passing through a convex lens, or reflecting from a concave mirror.

9. Law of reflection says that for specular reflection the angle at which the wave is incident on the surface equals the angle at which it is reflected. Mirrors exhibit specular reflection. 10. Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves. 11. Geometrical optics, or ray optics, describes light propagation in terms of "rays".

REVIEW OF RELATED LITERATURE

Law of Reflection Light is known to behave in a very predictable manner. If a ray of light could be observed approaching and reflecting off of a flat mirror, then the behavior of the light as it reflects would follow a predictable law known as the law of reflection. The diagram below illustrates the law of reflection.

[pic]

In the diagram, the ray of light approaching the mirror is known as the incident ray (labeled I in the diagram). The ray of light that leaves the mirror is known as the reflected ray (labeled R in the diagram). At the point of incidence where the ray strikes the mirror, a line can be drawn perpendicular to the surface of the mirror. This line is known as a normal line (labeled N in the diagram). The normal line divides the angle between the incident ray and the reflected ray into two equal angles. The angle between the incident ray and the normal is known as the angle of incidence. The angle between the reflected ray and the normal is known as the angle of reflection. (These two angles are labeled with the Greek letter "theta" accompanied by a subscript; read as "theta-i" for angle of incidence and "theta-r" for angle of reflection.) The law of reflection states that when a ray of light reflects off a surface, the angle of incidence is equal to the angle of reflection.

Plane Mirror

Light rays are coming from a source and reflecting off each point of the object ( AB) in all directions. For simplicity, only a few of the rays are drawn. The rays spread upon leaving the object, and then each ray reflects from the mirror according to the law of reflection. The eye extends back the diverging reflected rays to see an image behind the mirror. An image formed in this manner by extending back the reflected diverging rays is called a virtual image. A virtual image cannot be projected on a screen. The light does not physically come together, but rather, the eye (or camera) interprets the diverging rays as originating from an image behind the mirror. Due to the law of reflection, the image formed by a plane mirror is the same distance behind the mirror as the object is in front of the mirror.

[pic]

Concave Mirror

Light always follows the law of reflection, whether the reflection occurs off a curved surface or off a flat surface. The task of determining the direction in which an incident light ray would reflect involves determining the normal to the surface at the point of incidence. For a concave mirror, the normal at the point of incidence on the mirror surface is a line that extends through the center of curvature. Once the normal is drawn the angle of incidence can be measured and the reflected ray can be drawn with the same angle. This process is illustrated with two separate incident rays in the diagram at the right.

[pic]

If the light bulb is located at a different location, the same principles apply. The image location is the location where reflected light appears to diverge from. By determining the path that light from the bulb takes after reflecting from the mirror, the image location can be identified. The diagram below depicts this concept.
[pic]

Convex Mirror

A convex mirror is sometimes referred to as a diverging mirror due to the fact that incident light originating from the same point and will reflect off the mirror surface and diverge. The diagram at the right shows four incident rays originating from a point and incident towards a convex mirror. Each of these four rays will reflect according to the law of reflection. After reflection, the light rays diverge; subsequently they will never intersect on the object side of the mirror. For this reason, convex mirrors produce virtual images that are located somewhere behind the mirror.

[pic]

The image in the diagram below is a virtual image. Light does not actually pass through the image location. It only appears to observers as though all the reflected light from each part of the object is diverging from this virtual image location. The fact that all the reflected light from the object appears to diverge from this location in space means that any observer would view a replica or reproduction when sighting along a line at this location.
[pic]

When the object is located beyond the center of curvature (C), the image is located between the center of curvature (C) and the focal point (F). On the other hand, when the object is located between the center of curvature (C) and the focal point (F), the image is located beyond the center of curvature (C). Unlike plane mirrors, the object distance is not necessarily equal to the image distance. The actual relationship between object distance and image distance is dependent upon the location of the object (Mendez, 2010).

Pair of Parallel Mirrors

When the two mirrors are aligned at a 0-degree angle with each other (i.e., a parallel mirror system), there are an infinite number of images. Each image is the result of an image of an image, or an image of an image of an image or an image of an image of ... . The diagram below shows the multiple images for a parallel mirror system. Images I1 and I2 are primary images. Image I1 is the image resulting from the reflection of the object O across mirror M1 and image I2 is the image resulting from the reflection of the object O across mirror M2. Image I3 is an image of image I1, found by reflecting image I1 across mirror M2. Image I4 is an image of image I2; found by reflecting image I2 across mirror M1. This process could continue indefinitely, producing images of images for an infinite number of images.

[pic]

Multiple mirror systems are merely the extension of what we have already learned about plane mirrors. The locating of images is an extension of the principle that the image distance to the mirror is the same as the object distance to the mirror. Drawing ray diagrams for multiple mirror systems is an extension of the line of sight and law of reflection principles (Bradbury, 2009).

METHODOLOGY

Materials
Mirror
Plyboard or Plywood
Different pictures
LED lights
Nails
Wires
Switches
Electric tape
Black curtain

Procedure

1. Make a frame for the room using the plywoods having a size of 6’ x 2’ x 2’ with one side open for the entrance.
2. Cut 4 mirrors for 3 sides and the other one for the top. The size of the 3 mirrors should fit the frame leaving one inch margin from the edge for the LED lights.
3. Paint the interior with black.
4. Attach the mirrors then the LED lights using an electric tape.
5. Fix the switches of the LED lights on the bottom of the mirror.
6. Pin the black curtain in the opening of the frame.
7. Attach different background designs in the bottom or in the curtain facing the mirrors.

RESULTS AND DISCUSSION

The main purpose of the study is to determine the effects of different colors of lights and backgrounds on the reflection of the infinite mirror. It sought to compare the reflection of the mirror world (with presence of different colors of lights and different backgrounds) to that of other projects that used mirrors to show infinity.

Table 1. Comparison between mirror world and related projects

|Mirror World |Infinite Mirror |
|It shows infinity. |It shows infinity. |
|Only plane mirrors are used. |Only plane mirrors are used. |
|It has different colors of lights. |Some have lights but containing only one color. |
|Christmas lights are used. |Only a single bulb is used. |
|It has different backgrounds which can be changed. |Backgrounds are used but can’t be changed. |
|A person can enter inside. |A person cannot enter inside. |
|It is more expensive. |It is cheaper. |
|Facing mirrors are used |Single mirror is used (Appendix Figure 4) |

The comparison in Table 1 shows the similarities and differences between the mirror world and other projects that used mirrors to show infinity. Based on the comparison, mirror world and other infinite mirrors are the same in terms of the use of mirrors to show infinity. There are also some differences between the two in terms of the lights and backgrounds used. In the mirror world, different colors of lights are used using the Christmas lights. In other infinite mirrors, some have lights but only one color is used and most of the time a single bulb is only used. In terms of backgrounds, mirror world used backgrounds that can be changed while other infinite mirrors used only one background. In terms of being interactive, mirror world is indeed interactive because a person can enter inside and he/she can also choose the background that he/she wants. For other infinite mirrors, most of the size used is not enough for a person to enter. Mirror world is also more expensive compared to other infinite mirrors because of the size of the mirror. The mirror world shows infinity of the different colors of lights. As the reflection goes on, the lights tend to bend and make a curve. The visible end of the infinite reflection is just black. The mirrors having infinite reflection are the two mirrors facing each other. The other one without a mirror in front does not show any infinity. Other related projects having used of single mirror only, shows infinity because of the lights that were attached with a slight space from the mirror and were not Christmas lights like the one used in the project.

SUMMARY, CONCLUSIONS AND RECOMMENDATIONS

SUMMARY

This experiment was conducted to determine the effect of determine the effects of different colors of lights and backgrounds on the reflection of the infinite mirror. A wooden frame (6’ x 2’ x 2’), with one side open for the entrance, was made and four mirrors were cut, three for the sides and the other one for the top. One inch margin from the edge was made leaving a space for the LED lights. The interior was painted with black and a black curtain was attached at the entrance. Backgrounds were placed on the curtain and on the bottom part of the frame.

The different colors of lights made the backgrounds more visible inside the dark mirror world. The backgrounds made the mirror world more attractive because of the different colors and designs that can be seen through the reflection. The mirror world would also become more interactive because of the larger space where a person can enter inside.

CONCLUSIONS

This study revealed that the mirror world shows infinity of the different colors of lights. As the reflection goes on, the lights tend to bend and make a curve. The visible end of the infinite reflection is just black. The mirrors having infinite reflection are the two mirrors facing each other. The other one without a mirror in front does not show any infinity. Other related projects having used of single mirror only, shows infinity because of the lights that were attached with a slight space from the mirror and were not Christmas lights like the one used in the project. Most of the sizes of the infinite mirror projects are small that a person cannot enter.

RECOMMENDATIONS

Based on the conclusions, it is highly recommended to conduct the following:
1. This study can be revised by using cheaper type of mirrors or improvised materials.
2. The entrance may be installed by a door with another mirror for better reflection.
3. Spotlights with different colors focusing in mirrors may be used.

BIBLIOGRAPHY

• Mendez (2010). Laws of reflection. Lesson 3.http://www.physicsclassroom.com/class/refln/u13l1c.cfm

• Mendez (2010). Laws of reflection. Lesson2 http://www.physicsclassroom.com/class/refln/u13l3b.cfm

• Mendez (2010). Laws of reflection. Lesson1 http://www.physicsclassroom.com/class/refln/u13l4a.cfm

• Mendez (2010). Laws of reflection. Lesson6 http://www.physicsclassroom.com/class/refln/u13l2f.cfm

• Bradbury (2009). Geometrical optics. Physics lesson. http://www.cliffsnotes.com/study_guide/Geometrical-Optics.topicArticleId-10453,articleId-10441.html

• Hecht, Eugene (1987). Optics (2nd ed. ed.). Addison Wesley.Chapters 5 & 6.http://en.wikipedia.org/wiki/Geometrical_optics

• Mungan, C.E. (1999). "Faraday Isolators and Kirchhoff's Law: A http://en.wikipedia.org/wiki/Mirror

• Moreno (2010). "Output irradiance of tapered lightpipes"http://en.wikipedia.org/wiki/Reflection_(physics)

APPENDIX FIGURES

[pic]

Appendix Figure 1. The mirrors were attached leaving a space for the LED lights.

[pic]

Appendix Figure 2. The upper view after attaching the mirrors

[pic]
Appendix Figure 3. Sample Project of Infinite Mirror

[pic]
Appendix Figure 4. Sample Project of Infinite Mirror using one mirror only