Light Absorption

Type 

Physical Science  

Grade Level

Upper Elementary (Grades 4 and 5) and/or Middle School (Grade 6) 

Difficulty of Project

Cost

Under $6.00 excluding the Tri-fold display board 

Safety Issues

Do not shine the flashlight directly into the eyes. 

Material Availability

The materials required for this project are readily available and inexpensive. 

Approximate Time Required to Complete the Project

Under one hour. Also between 1 and 2 hours to prepare the Tri-fold board display. 

Objective

When white light shines on a colored object all of the colors that form the white light are absorbed except the color of the object which is reflected. A filter is a transparent material that absorbs some colors and allows others to pass through. The research aspect of this science fair project is to test the effect of different colored lights on the color of objects using filters. 

This science fair project focuses on the use of filtered colored light to investigate the concept that the color of an object is based on the color of light that it reflects. Using red, blue, and green pieces of paper light of various colors, made possible by the use of colored filters, will be directed on the paper pieces, and the colors seen recorded in a data table. The control for this project will be to shine white light with no filter in front of it, directly on the paper pieces which will show their actual colors. This is because the specific color is reflected off the paper, while the rest of the colors that make up white light are absorbed. 

Materials and Equipment / Ingredients

Flashlight, red, blue, green construction paper, see-through color cellophane paper, or camera filters one of each of the colors (red, blue and green), and masking tape or a rubber band.

Introduction

Color filters will let through only the color they are and absorb all other colors. So when blue light is allowed through a blue filter onto a blue object, the object will still reflect blue and therefore appear blue. But when blue light from a blue filter hits a red object, it will be absorbed and no light will be reflected, giving the object an appearance of being black. This idea is illustrated below.

• http://warneronline.com/img_lg/720310_set_of_filters.jpg
• http://www.pgo-online.com/grafix/components/schott_color_glass.jpg
• http://www.olympusmicro.com/primer/photomicrography/images/filters/colorfilters.jpg