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This Prelab asks you to build, and thus take ownership of, the so called "thin lens equation". This activity will walk you through the derivation of a very useful expression that will used during the lab. To do so, we will use figure 18.46 from your lecture text. Remember: The purpose of the Prelab is to have a recording of your thoughts about the subject matter we are going to explore, prior to engaging in the Lab activities. Prelabs themselves are graded for completion only, and there is no penalty for incorrect responses. h Far focal point Near focal point s' - f s' 0 2015 Pearson Education, Inc. Q.1 The two shaded triangles in the diagram are similar triangles. Use that fact to complete the following expression: h s' - f h Q.2 The ray that travels through the center of the lens creates another set of similar triangles. Use that fact to provide a different expression for the same ratio: h' S' h F Q8.3.3: If A=B and A=C, it must be that B=C, so, set the righthand side of the equations equal to one another, divide by s' and simplify to arrive at the thin-lens equation. h ' s I - -+ h f S - (S) f S' - f = S f