University Physics Young and Freedman Chapter 34 Concept Questions and solutions Chapter 34: Pre-Chapter Question Q: Why do large telescopes use mirrors rather than lenses to collect light and form images? A: Lenses are plagued by chromatic aberrations. By contrast, mirrors are intrinsically free of them. Plus the shape can be maintained by supports along its back surface. 1. If you walk directly toward a plane mirror at a speed v, at what speed does your image approach you? When you are a distance s away from the mirror, your image is a distance s on the other side and the distance from you to your image is 2s. As you move toward the mirror, the distance 2s changes at twice the rate of distance s, so the speed is 2v. 2. A cosmetics mirror is designed so that your reflection appears right-side up and enlarged. Is the mirror concave or convex? To see an enlarged image, where should you place the mirror relative to your face? Convex – erect, but small, so use a concave mirror. The image will be enlarged if the
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This note was uploaded on 04/18/2008 for the course PHYS 0030 taught by Professor Cutts during the Spring '07 term at Brown.