Light Brightness Affected by Fog Arvind Selvakesari Shanghai American School 12/05/09

Size: px

Start display at page:

Download "Light Brightness Affected by Fog Arvind Selvakesari Shanghai American School 12/05/09"

Alan Preston
6 years ago
Views:

1 Light Brightness Affected by Fog Arvind Selvakesari Shanghai American School 12/5/9 The Question Which coloured light bulb will have the least brightness change from normal to foggy conditions. The Plan Independent Variable: Values chosen for investigation: The different coloured LED s: Red, Green, Blue, and yellow Controlled Variables: The normal and foggy environments will be held constant. Set Up: This is my experiment setup. The Smoke containing box has an circuit board with LED s connected to the circuit board outside the box. The light sensor is also inside the box, connected to a Logger Pro device outside the box to take my data.

As you can see, there are many materials and components used to produce my data collection. This is a close up of where all the data collection will take place.

2 As you can see, there are many materials and components used to produce my data collection. This is a close up of where all the data collection will take place. Expectations My expectation for this experiment was that each colored light bulb s brightness will decrease in foggy conditions. Red bulbs are most commonly used in the environment surrounding us. Red bulbs are in airport runways to direct and pilot, they are in cars to warn drivers of the presence of a car in front of them. This color is bright and a good color to grab a human s attention. Since airport and cars use them in all kinds of weather, I believe that the red bulb will have the least amount of brightness change. Although red is commonly used, so is yellow. From my research, yellow light bulbs emit some of the longest wave lengths, allowing it to shine the brightest in liquids, and possibly in fog. So my hypothesis is that the red and yellow bulbs would have the least amount of brightness change in normal to foggy conditions. SAS 12/12/9 2:42 PM Comment: Very nice, clear figures that help the reader to understand what you did. Usually, it is helpful to label each figure as 1, 2, etc. for easy reference.

How I Tested my Experiment I tested the experiment enclosing the box as much as possible, so that the least amount of light and wavelengths are detected for better readings.

3 How I Tested my Experiment I tested the experiment enclosing the box as much as possible, so that the least amount of light and wavelengths are detected for better readings. I would then turn on the Light sensor and the LED. If I had to put smoke paper inside, I would quickly open the foam used to close the box, and put the smoke paper inside. My Data Tables after putting them in Excel Each tables time is in seconds, and is a unit of measure for brightness. All lights no smoke Time Blue Light no smoke Time

4 Green Light no smoke Time Red Light no smoke Time Yellow Light no smoke Time Comments on data table: Before I put the smoke inside the box, I did a few tests to see the initial brightness of each LED. The brightness order goes like this: Blue, red, yellow, and green. This is very important data because it is the benchmark against which each LED s brightness will decrease. All Lights with smoke Average brightness of LED s with smoke LED Green 43 Red 372 Yellow 3 Blue 843 Due to the length of the data table, only a small portion of the data is shown on the tables. If needed, request the extended data collection tables.

5 Table Explanation: As you can see, the table showing the data of the lights switched on with the smoke, has a decrease of brightness. The graph is fluctuating because of the smoke travelling and distorting the light waves. The smoke cannot be controlled. But you can see the decrease of brightness with smoke from the averages of the individual bulbs. Look at the graphs for an clearer picture. Graphs of Data 3 All lights no smoke 25 Brughtness () Time (sec) This is the graph when all the lights were switched on without the smoke. The average brightness of this test was The minimum brightness of the lights was 2514, and the maximum brightness was The blue line at the start of the graph is when the lights weren t switched on. The line above it is the line when the lights were switched on.

6 Brightness () Blue Light only Time (sec) This is the graph when only the blue light was switched on, without the smoke. The average brightness of this LED was 859. The minimum brightness of the light was 845, and the maximum was 88.. The blue line at the start of the graph is when the lights weren t switched on. The line above it is the line when the lights were switched on Green Light Only Brightness () Series1 Time (Sec) This is the graph for when the Green LED was switched on. The average brightness was 113. The minimum brightness was 18, and the maximum brightness was 125. The two blue lines at the start of the graph is when the lights weren t switched on. There are two lines on the top because the darkness of the box was fluctuating, due to light somehow entering the box, or the fluorescent light waves being detected by the light sensor. The line above it is the line when the lights were switched on.

8 Red Light only Brightness () 7 6 5 4 3 2 1 Series1 Time (sec) This is the graph for when the red LED was only switched on. The average brightness was 672.

7 8 Red Light only Brightness () Series1 Time (sec) This is the graph for when the red LED was only switched on. The average brightness was 672. The minimum brightness was 65, and the maximum brightness was 729. The blue line at the start of the graph is when the lights weren t switched on. The line above it is the line when the lights were switched on. Brightness () Yellow Light Only Time (Sec) Series1 This is the graph for only when the yellow LED was switched on. The average brightness was 128. The minimum brightness was 12, and the maximum brightness was 136. The blue line at the start of the graph is when the lights weren t switched on. The two lines above were when the lights were switched on. There are two lines at the top of the graph because the brightness readings from the light sensor kept fluctuating. But before the two lines split up is what the graph would look like without the fluctuation.

8 Brightness () Comparision of Indivisual Light Brightness Time (sec) Blue Light Green Light Red Light Yellow Light This is how the separate graphs of each coloured LED look like when compared together. The blue light is the brightest because it is the closest to the light sensor, but if the red light was in the same position as the blue, it would be the brightest. Yellow and green were the same distance from the light sensor and were the furthest away from the light sensor. But even if they were closer, they wouldn t be the brightest lights. This graph represents my data collection of the brightness of the lights when smoke was present inside the box. Since I didn t want the variable of the smoke to change too dramatically, I had to get my reading fast. The start of the graph is

9 when all the lights were switched on with the smoke starting to form. The gradual decrease in brightness is due to the smoke accumulating inside the box. Then the sudden drop in my graph is when I inserted an extra smoke creating paper. When the brightness of all the lights with the smoke became constant I started testing each light bulb s difference in brightness with smoke. Each colour s data is indicated on the graph. The sudden drops at an end of a colour s data collection was when I had to switch the electricity flow into another coloured LED. Green LED s average brightness was 43, Red lights average brightness was 371, yellow lights average brightness was 3, and blue lights average brightness was 843. Analysis of Data Initially before the test, I did some research on which lights were the brightest, which were the most dull lights, and which lights worked best in foggy conditions. From my research, the yellow light was the brightest light in foggy conditions. This was because the longer the wavelength of an light, the brighter it is in foggy conditions. And yellow lights have long wavelengths of nm(or nanometer). Then through my own comprehension, I figured that the red light should also be bright in foggy conditions because its wavelength was 66 nm. So my hypothesis was that the yellow and red LED s should have the least amount of change from normal to foggy conditions. After conducting my experiment, I tried making sense of the data. I was trying to look for which coloured LED had the least amount of change from normal to foggy conditions, not which was the brightest. So I did some math to come up with the following statistics. The Green LED brightness changed 7 from normal to foggy conditions, which is about a 2.63% decrease in brightness from normal conditions. The red LED s brightness changed by 31, which is about a 1.81% decrease from normal conditions. The yellow LED s brightness changed by 98, which is about a 4.2% decrease from normal conditions. The blue LED brightness changed 16 from its normal to foggy conditions, which is about 1.2% decrease. Meaning that the order of least brightness change from normal to foggy condition is: blue, green, red, yellow. But after doing my experiment, I noticed the Blue LED s brightness did not change at all. The readings with smoke and without smoke are almost the same. The reading without the smoke said 859 and that with smoke was 843. This meant that something was wrong with my set up, because all of the other lights showed a significant change in their normal to foggy conditions. I expected a drastic change to occur, but the blue LED didn t do so. Nor did I expect the yellow LED to change so much. Based on my research yellow should be the brightest, but turns out it isn t. So, as you can see there are some flaws in my experiment s data collection, but I have rectified them. The blue LED had the least change because it was only 1 or 2 centimeters away from the light sensor, while the others were further away. This means that when I inject the smoke, there would be less smoke disrupting, and changing the brightest of the LED, because there is less space for the smoke to distort the brightness. And since the other three LED s were further away, they had more smoke distorting their brightness. The second mistake was to not make each LED face the light sensor directly. I was struggling for space to fit all the LED s close together so that they SAS 12/12/9 2:44 PM Comment: This is good, but it would be appropriate to also show these numbers in a table. SAS 12/12/9 2:45 PM Comment: Very nice analysis

10 all gave a descent reading. But unfortunately I learned that one or two bulbs would face the light sensor directly, and the others could not. This prevented some bulbs from displaying their real brightness, therefore making my data not very precise. Conclusion As we can see from my experiment, it is confirmed that a light s brightness will reduce in foggy conditions. But the way my experiment is set up doesn t really show the true numbers in the data collection. So the next time I do the experiment I will try and make each LED the same distance away from the light sensor, and make sure that each bulb is directly facing the light sensor. This experiment was inspired by real world applications. Red bulbs are most commonly used in the environment surrounding us, because of its high brightness. Accordingly green lights aren t that common since it is dull. If a pilot was flying a plane in very bad weather conditions, he would rely on the airport s bright red lights to penetrate the fog, and his blue lights on the plane to indicate the presence of a plane. When he reaches closer to the ground the yellow lights are lit everywhere to highlight the runway for a safe landing. As I was curious to understand why airports and airplanes use these different coloured lights, I came up with this experiment to see how the brightness of these lights change in foggy conditions. Overall I think it was a good learning experience. I proved my hypothesis wrong through my experiment, but through my research I have proven it correct. This was an extremely challenging experiment for me because there were so many things that could go wrong and affect my data. I had to use many concepts and skills to produce the results. For example, I had to use two circuit boards, with a battery, resistors, and wires to generate the light. Then I had to set of my smoke containing box with my light sensor, and make a few modifications to ensure my readings were accurate. After spending so much time and effort, I realized my readings are partially incorrect. This taught me how to address my mistakes in a lab and how to improve the tests next time to get more accurate readings. FINAL COMMENTS from Mr. Happer December 11, 29 Student: Arvind Controlled Experiment Criteria Score Comments Tables, Graphs, Clarity 4+ Very nice. While there are a few minor suggestions (see comments) the overall work on this experiment is truly exceptional! Concepts, Reflections 4+ Outstanding work, Arvind!

Home-made Infrared Goggles & Lighting Filters. James Robb

Home-made Infrared Goggles & Lighting Filters James Robb University Physics II Lab: H1 4/19/10 Trying to build home-made infrared goggles was a fun and interesting project. It involved optics and electricity.