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Instructions: Go the PHET web site and select the Bending Light simulation. The following link will take you directly to the simulation: http://phet.colorado.edu/en/simulation/bending-light If you click on the picture and then click on "Intro" - it will prompt the following dialog window: Material Worm Bending Light PhET Procedure Part 1: Finding the relationship between directions of light refraction and light reflection. It is recommended that you spend some time familiarizing yourself with the simulator before starting the actual lab. The red button on the laser turns the light on. Intensity meter measures the intensity of light relative to incident in %. Move the source of light. What do you notice about the angles of the reflected and refracted light? Briefly, give a qualitative description of the following features: What happens to the reflected and refracted rays as you change the angle of the incident light beam? . . . What does changing the index of refraction do to the refracted and reflected light? . . . For air-water interface (incident medium-refraction medium): use the protractor to measure the angles of incident, reflected, and refracted rays. For convenience (and by convention), angles are measured relative to "normal" (as starting from the vertical axis and going down to the laser beam. The same goes for the refracted beam - but now you will want to measure from the z-axis up to the beam.) When incident angle is 60 deg what is the value of angle for the reflected ray? ... Refracted ray? ... Measure the intensities of refracted and refracted light while moving the source of light for incident angle with the increment of 10 deg. Record your measurements in the Table 1 below: Table 1 Angle of the Angle of the Intensity of the Angle of the Intensity of the incident ray reflected ray reflected ray refracted ray refracted ray 80 deg 70 deg 60 deg 50 deg 40 deg 30 deg 20 deg Do the intensities of reflected and refracted rays add up to 100%? ... Do the angles of reflected and refracted rays add up to a certain number? ...Part [1: Finding the relationship between directions of light refraction and light reection. Goal of this section is to nd a mathematical expression for what you were seeing in Part I. 1) Find a relationship relating the angle of the incident light and reected light. Write an expression relating 9,\" c and 9w,1 using the data in Table 1. 2) Find a relationship relating the angle of the incident beam to the angle of the refracted beam. This one isn't quite as easy to see right away, and you might have to nd a way to use the data in Table 1 to gure out the relationship. Here is a hint to get you started: the general relationship for this situation is given by: Here 8 are the angles corresponding to either the medium on top or bottom, and n and m are the indices of refraction of either the top or bottom material. Your job is to come up with a way of guring out which variable corresponds to which material. The easiest way is to take 11 as the bottom material, then n/m relationship will be always equal to 1.33 (1.33/1.00). Verify using the data in Table 1 that this is correct assumption. Take ratios for all 7 measurements, average them and report (n/m) compare to the expected value of 1.33 and calculate percent error. 3V, Part II: Finding unknown index of refraction. Total internal reection. Choose glass for medium #1 and mystery B for medium #2: A) Place the source of light as shown in the gure. Move the source of light carefully until you observe the refracted ray disappearing completely in the Mystery medium B. Measure the angle of incident ray. Use this value and the equation for critical angle (given in the Introduction) to nd the index of refraction for the Mystery Medium B. Report it below: B) Switch to \"More Tools Ta \". Make the same setup and measure the speed of light in Mystery Medium B. Record it below. Is it slower that the speed of light in vacuum? Use this value to calculate index of refraction for the medium. Compare to the value obtained in Section A. Part III: Prisms and light dispersion. Now switch to the tab titled \"Prisms\" Turn on the laser. Try playing around with the various sorts of prisms and answer the following (a couple of sentences per answer is sufcient): A) Are the reection and refraction of light color- dependent? How can you tell? B) Which shapes split the white light into different colors the best? Is there a particular set-up that you found demonstrates this well? C) Set 11 for environment to \"air\" and n for the prism to \"glass\". Drag the triangle prism into the path of the laser. Click on the Normal button on the bottom right. Draw the light rays, prism, and normal for your conguration below. Click on the protractor button & complete Table 2. Incident angle (as close to the Refracted angle shown values as possible) 30 deg 40 deg D) Setup your experiment with the prism as shown on the gure above. Make sure that the 380 nm line is \"on\" and it is running exactly along the 90 deg line on the protractor. Switch the wavelength all the way to T00 nm and record the best you can by how much the angle changed. E) Switch to \"white light\" of the light source, button ( [:0 on the right panel. Change the light to white light. Rotate the prism until the light that comes out the other side of the prism is separated into the color spectrum. Draw your conguration indicating where the red and blue light is. What color of light refracts more when moving through the prism? WHY? F) Given that white light can be split, try to make a situation where light forms a rainbow. Knowing that rain drops produce rainbows try to use prism of a similar shape. Place the screenshot below. Now place second prism of the same shape in the light path did the rainbow change. Describe your observations. Can you make a double rainbow in any way