Understanding Refraction
Ever wondered why a straw looks bent in a glass of water? That's refraction in action - light changing direction when it travels between different materials (called mediums).
When light enters a denser material like glass or water, it slows down and bends towards the normal line (an imaginary line perpendicular to the surface). Moving into a less dense material has the opposite effect - light speeds up and bends away from the normal.
The refractive index tells us how much a material will bend light. You can calculate it using n = C/V, where C is light's speed in a vacuum and V is its speed in the material. There's also n = Sin I/Sin R, comparing the angles of incoming and refracted light.
Key Point: The critical angle occurs when refracted light runs exactly along the surface of a material - this is essential for understanding total internal reflection.
