A laser beam in air strikes a flat acrylic block (index 1.49) at an incident angle of 35° from the normal. Immediately beneath the acrylic is a large tank of water (index 1.33) whose upper surface is flush with the bottom face of the acrylic. The laser enters the acrylic, crosses it without hitting the sides, and then enters the water.
Answer the questions below. Base all explanations on qualitative comparisons of indices rather than explicit calculations.
(a) At the air–acrylic boundary, state whether the beam bends toward or away from the normal. Explain your reasoning.
(b) At the acrylic–water boundary, state whether the beam bends toward or away from the normal of that surface. Explain your reasoning.
(c) Compare the overall direction of the beam in the water with its original direction in air. Does the emergent beam in water lie closer to the normal, farther from the normal, or along the same direction as the initial incident beam? Provide a qualitative justification that synthesizes your answers to parts (a) and (b).