Education Technology

Bell Ringer: Light Intensity vs. Distance

Activity Overview

Students derive the equation relating the intensity of light at a given point to the distance of that point from the light source.

Key Steps

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    Students derive the relationship between light intensity and distance from the light source. They begin by writing and graphing the equation relating the surface area of a sphere to the radius of the sphere.

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    Next, they derive the equation for light intensity as a function of the power of the light source and the distance from the source. They graph this function as well.

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    Finally, they use the graph of intensity vs. radius to solve some problems about the power of an unknown light source.