Learning Objectives A. Describe what happens to light when it shines upon and though medium. B. Explain how light direction changes at the interface between two media and what determines the angle. C. Describe the effect of varying wavelength on the angle of refraction. D. Explain why a prism creates a rainbow. E. Apply Snell's law to a laser beam incident on the interface between media. Everyday Physics in your life: I put a straw in a glass of water as shown in the picture on the right. What do you notice? (2) Try this at home with some other things like a spoon or fork. Do you observe any different things? (1) What ideas do you have about why things look different under water? (2)