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Unformatted text preview: PHYS 4D Solution to HW 4 January 28, 2011 Problem Giancoli 32-1 (I) When you look at yourself in a 60-cm-tall plane mirror, you see the same amount of your body whether you are close to the mirror or far away. (Try it and see.) Use ray diagrams to show why this should be true. Solution: See Fig.(1). Because the angle of incidence must equal the angle of reflection, we see from the ray diagrams that the ray that reflects to your eye must be as far below the horizontal line to the reflection point on the mirror as the top is above the line, regardless of your position. Problem Giancoli 32-3 (II) Two plane mirrors meet at a 135 ◦ angle, Fig. 32-45. If light rays strike one mirror at 38 ◦ as shown, at what angle ϕ do they leave the second mirror? Solution: See Fig.(2). The law of reflection can be applied twice. θ = 38 ◦ , α = 135 ◦ , θ + α + ϕ = 180 ◦ ⇒ ϕ = 7 ◦ . Problem Giancoli 32-5 (II) Show that if two plane mirrors meet at an angle ϕ , a single ray reflected successively from both mirrors is deflected through an angle of 2 ϕ independent of the incident angle. Assume ϕ < 90 ◦...
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This note was uploaded on 09/19/2011 for the course PHYS 4d taught by Professor Staff during the Winter '08 term at UCSD.
- Winter '08