Group Problem #18 Physics 112-1 F12 Page 4 of 4

Group Problem #18 Physics 112-1 F12 Page 1 of 4

Group problem #18: Refraction and reflection

One afternoon while you are bored while studying for your Physics final, you decide to figure out some things about your CD player. You realize that the laser bean that “reads” the information from a compact disc is D=0.737mm wide when it strikes the disk. It forms a cone with a half-angle of θ = 27.0° . It then passes through a 1.2 mm think layer of plastic with refractive index 1.55 before reaching the reflective information layer near the disc’s top surface. As extra practice for your Physics final, you decide to calculate the diameter of the beam d at the information layer?

You are spending time at the pool with your friends on a Saturday afternoon. While under water, you look up and notice that you see objects above water level in a circle of light of radius Group Problem #18 Physics 112-1 F12 Page 2 of 4 approximately 2.0m, and the rest of your vision is the color of the sides of the pool. You start to wonder how deep below the surface of the water you are. Once you get back to the surface, you decide to calculate how deep you actually are.

You are 3m underwater looking up at your friend holding a ball over the water. To your eyes, does the ball appear closer to the water, farther away from the surface of the water or the same distance compared to the actual distance from the surface of the water. If the actual distance Group Problem #18 Physics 112-1 F12 Page 3 of 4 above the water is 1.3m, how far above the water does the ball appear to be? Does this agree with your earlier assessment?

The index of refraction of a diamond is 2.42. A beam of light strikes the surface of a diamond in a room of air at an angle of 28°. Is part, all or none of the beam reflected off the surface of the diamond? Why? Group Problem #18 Physics 112-1 F12 Page 4 of 4

If the diamond is submerged in water (n=1.33) instead of air, what will happen to the incident beam? Why?