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Unformatted text preview: April 7, 2009 PHY2054 Discussion-Spring ‘09 Quiz 8 (Chapter 22.7-23.5) Name: UFID: *1. (2.5pts) A diamond is placed on the bottom of a 1.60 m-deep swimming pool. A circular raft floats on the surface of the water directly above and centered on the diamond. If the water of the pool has a refractive index of 1.38, what is the minimum diameter of the raft to hide the diamond from an observer above the surface of water? Since the light rays incident on the water surface with an angle larger than the critical angle undergo total internal reflection, thus it is enough to block the rays with an angle of incidence smaller the critical angle. When the diameter is minimal, the light ray incident on the water surface at the critical angle strikes the edge of the raft. Therefore, we have nsinθ C = 1 θ ⇒ C = sin-1 (1/n) = sin-1 (1/1.38) = 46.4º d min = 2r min = 2htanθ C = 2×1.6×tan46.4º = 3.36 m *2. (2.5pts) It is observed that the size of a virtual image formed by a concave mirror is twice the *2....
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- Fall '08
- Physics, Snell's Law, Total internal reflection, Surface