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3. You are working for a lab that studies thin film interference. One day, you mix up the labels on blocksof material for a thin film experiment. You could cut a thin layer off each block of material and testthem that way; however, that would take a lot of time and waste material. You need to figure outwhich is the correct block of material to use. However, you do remember one thing: when you shine light through the left corner of the correct block,no light comes out of the top corner of the block. The light is totally internally reflected, no matter-what the incident angle is (that is, for any incident angle between 0° and 90°).

O What is the minimum possible value of n2 required for this to happen? You figure out that there is a thin film experiment you can do without cutting the unknownblocks. First, you place a thin layer known material n3 on top of the block of material. You shinelight with wavelength A from air directly onto the thin film n3. By changing to different thin filmmaterials, you can vary the value ofn3.

Explain in detail how you can use the rules for constructive and destructive interference to deter-mine the value of n2.

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