Critical Angle The incident angle that causes the refracted ray to skim right along the boundary of a substance is known as the critical angle,  c.
{"Image DocumentName": "Axle Analogy overhead view sidewalk grass \uf071r", "Image ImageDescription": "Imagine you\u2019re on a skateboard heading from the sidewalk toward some grass at an angle. Your front axle is depicted before and after entering the grass. Your right contacts the grass first and slows, but your left wheel is still moving quickly on the sidewalk. This causes a turn toward the normal. If you skated from grass to sidewalk, the same path would be followed. In this case your right wheel would reach the sidewalk first and speed up, but your left wheel would still be moving more slowly. The result this time would be turning away from the normal. Skating from sidewalk to grass is like light traveling from air to a more. overhead view. optically dense medium like glass or water. The slower light travels in the new medium, the more it bends toward the normal. Light traveling from water to air speeds up and bends away from the normal. As with a skateboard, light traveling along the normal will change speed but not direction. sidewalk. grass. \uf071r.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}