Our group chose to do an experiment on the Crooke Radiometer. A radiometer is actually an interesting scientific device that spins due to light and heat. It’s interesting because it uses something so simple, heat and light, and somehow the vanes move inside the radiometer. The scientific explanation behind this device is explained as heat energy. Within the vacuum, there contains four vanes with both a black and silver side to them. When light strikes these vanes, the black side of the vain will absorb more of the lights energy. When this occurs there is a temperature difference, which results in a formation of an air current, making the vanes move in a foreword direction.
We found out that people hypothesized that the higher the intensity of light the more RPMS or rotations per minute there are. In our experiment we wanted to test the theory of distance, light intensity, light color to see if there was a correlation to how fast the radiometer vanes spin. If the results we obtain are significantly influential, then we would make predictions of possible ways to form energy through the suns light with a moving turbine. To test the different theories we used a radiometer, a ruler, LED shake light (1 watt), 20 Watt Light, Sunlight, Flashlight(1.5 watts), different colored transparency paper and a Photogate Timer to measure the rotations.
Theory of Distance- we wanted to see if the distance of the light source made a difference in the radiometer rotations. We placed the radiometer on the base of the Photogate Timer and set it to pulse, which allowed us to get a reading on the rotations. We place the light source at different distances (0 in, 3in, 5in, 10in) and recorded our results to see if there was a correlation between distance and rotations.
Theory of Light Color- We wanted to see if there was a correlation between the color of light and the radiometer rotations. Once again we used the Photogate Timer to measure the rotations. We used four different colored transparencies (blue, red, yellow and green). We held the color sheet in front of our light source at a set distance of 0inches away from the radiometer and recorded our results.
Theory of Light intensity-We wanted to see if there was a relationship between the intensity of the light source and the spins of the radiometer. We used the Photogate Timer to record the rotations yet again. We used four different light sources (flashlight, LED flashlight, 20 watt light, Sunlight). We place the different light source at a set distance of 0inches away from the radiometer and recorded our results.
Results-We found that the distance of the light did affect the radiometer rotations; the closer the light the faster the vanes spun. We also found that there was a relationship between the color transparencies and the rotations of the radiometer. We aren’t sure of the reason, but the green transparency made the radiometer spin slower than the other three colors. Finally, we also found a strong correlation between the light intensity and the radiometer rotation speed. Natural sunlight made the radiometer spin the fastest. We also noticed the higher the wattage of the light, the faster the vanes spun. Below are graphs we constructed to show our results.
Overall, our presentation was an enjoyable experience. It was really interesting to teach something we created to a group of students. It seems that all of the students in the class were excited about the experiment topic. I feel that the class would have enjoyed using the radiometer themselves but that might be something to look forward to into the future. I also believe that the students would take away more from our project if they were connected to a computer in order to effectively see the table of results. Overall it was a great learning experience for everyone