How can the strength of light be measured?- the effect on degradable materials

Light has some benefits and some hazards. In tunnels and roads, sufficient light offers a safer driving condition, while low light creates hazards and accidents. Photographers need to measure the amount of light in order to adjust their camera and produce a clear picture.
 Project description
In this project you will study light measurement and the effect of light on degradable material. You may purchase a light meter or by spending about $20 you can build your own light meter as a part of your project.
 Details of this project
More details or support for this project is available for the members of  Material needed for this experiment or a science kit about this title may be available at