Refraction is a fundamental phenomenon in physics where light bends as it travels from one medium to another. When light passes from air into water, or from air into glass, it changes direction. This bending occurs because light travels at different speeds in different materials.
Light bends because it travels at different speeds in different materials. In air, light moves very fast, but in water or glass, it slows down significantly. When light waves enter a denser medium at an angle, they compress and change direction. This is similar to how a car wheel turns when one side hits sand while the other is still on pavement.
Snell's Law mathematically describes refraction. It states that n1 times sine of theta1 equals n2 times sine of theta2, where n is the refractive index of each material and theta is the angle from the normal. The refractive index tells us how much light slows down in that material compared to vacuum. Air has a refractive index of about 1, while glass is typically 1.5.
The direction of bending follows a simple rule. When light goes from a less dense medium to a more dense medium, like from air to water, it bends toward the normal line. When light goes from a more dense medium to a less dense medium, like from water to air, it bends away from the normal. This happens because light slows down in denser materials and speeds up in less dense materials.
Refraction has countless applications in our daily lives. Eyeglasses use refraction to correct vision problems. Camera lenses focus light to create sharp images. Microscopes and telescopes use multiple lenses to magnify distant or tiny objects. Prisms split white light into beautiful rainbows by refracting different colors at slightly different angles. From fiber optic internet cables to the simple magnifying glass, refraction is fundamental to modern technology and helps us see and understand our world better.