quiz4answerkey - Quiz 4 Rubric Code QQQQQQ Withheld Student...

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Unformatted text preview: Quiz 4 Rubric Code: QQQQQQ Withheld Student ID: DL Section #: 2 Last Name: I certify that I will abide by the UC Davis Code of Academic Conduct Physics 7C Winter 2010 Martin First Name: Damien Signature: Lig m fro ray ht Plopper the Pig is stranded in the desert. He thinks he sees a lake in the distance but, since he is a smart pig, he knows it is only a mirage. What looks like a lake is actually the blue sky. The fact that it looks like it is on the ground is an illusion created by refraction. Letʼs develop a simple model to explain how mirages work. tch pa of Note angle the same (total internal reflection) sky Region 1 All normals shown Region 2 Region 3 Region 4 Region 5 Ground Apparent location of “lake” 1: It turns out that the index of refraction of air depends on the temperature of the air. In the picture above the temperatures in each region go from cold in Region 1 to hot in Region 5. Mathematically: TRegion 1 < TRegion 2 < TRegion 3 < TRegion 4 < TRegion 5. In order for the ray pictured to reach Plopperʼs eyes, rank the indices of refraction for each region from the highest (slowest velocity of light) to the lowest (highest velocity of light). Briefly explain your decision. The light bends away from the normal as we go from region 1 to region 5. Therefore the index of refraction is decreasing: n_1 > n_2 > n_3 > n_4 < n_5 (Alternatively, just the T.I.R. between regions 4 & 5 tells me that region 5 must have a smaller n than region 4) 2: Continue the ray from the patch of sky to Plopperʼs eyes in the illustration above showing how it bends at each region boundary. Make sure to also draw the normal at the correct point at each boundary. (Hint: in order for the “lake” to appear where it does in the illustration the ray needs to enter Plopperʼs eyes along the dotted line. To do this, the ray needs to reflect at some point, and it canʼt reflect off the ground.) See figure 3: Plopper is nearsighted (he canʼt see objects far away very well) which is why he is wearing glasses in the picture. What type of lenses, converging or diverging, are in his glasses to correct this problem? Describe where the image needs to be formed; what sort of image it needs to be, and why the selected lens can do the job. * The glasses need to create a virtual image between his near and far points. (A real image would be on the "wrong side" and he could not focus on it) * The far point is the issue. We need the virtual image to be closer than the object. * Therefore the lens must be diverging (a virtual image from a converging lens is always further away than the object) Image (closer, virtual) Equations X F.P. Object ...
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