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Across 5. Materials that do not allow light to pass through 6. Thicker at the center than it is at the edges 7. Bouncing of light from a surface

Down 1. Materials that allow only some amount of light to pass through 2. Thicker at the edges than it is at the center 3. Materials that allows light to pass through 4. Bending of the light as it moves from one material to another