Light Intensity Lab
An ultraviolet interference filter created by transparent materials.Copyright 2007 Barr Associates, Jet Propulsion Laboratory, NASA, Wikimedia Commons http://commons.wikimedia.org/wiki/File:Dichroic_filters.jpg
Students complete this Beer's law activity in class by examining the attenuation of various thicknesses of transparencies. From this activity, they come to understand that different substances absorb light differently. This concept is transferred to x-rays to explain that different substances absorb x-rays differently, hence the need for dual-energy analysis. In looking at Beer's law, students use the properties associated with natural logarithms. To conclude the activity, students complete a series of questions and calculations.
Light attenuation and Beer's law are concepts that are very important to many engineers. Environmental engineers must understand these concepts when designing solar panels as a means of alternative energy. Biomedical engineers apply these concepts to bone mineral density measurements using x-ray machines, as well as other broader applications such as the design of biomaterials.
After this activity, students should be able to:
- Derive the relationship between light and number of layer of attenuation.
- Perform experiments to illustrate the concept of attenuation.