Light sensor probes are useful in experiments that investigate seasonal variations and the nature of light. However, having a dedicated light probe is not always possible or even convenient for many instructors. Modern smartphone technology gives instructors the ability to use built-in light sensors as an inexpensive alternative. This introductory experiment will have students use a smartphone loaded with a light detection app to quantitatively determine how changing latitude on Earth changes flux received. The purpose is to have students discover how the different seasons arise from the Earth-Sun system. While performing the experiment and analyzing the data, students will also discover the following important and relevant physical relationships: distance from light source and light brightness (flux), latitude and flux, and Earth’s orientation and location (latitude) of maximum flux. By piecing all of these relationships together, students are able to explain the origins of the different seasons based on the data they collected.

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