Here's why:
* Light travels at different speeds in different mediums. Light travels faster in air than it does in glass.
* When light crosses the boundary between two mediums, it changes direction. This change in direction is called refraction.
The amount of bending depends on the angle of incidence (the angle at which the light hits the glass) and the refractive index of the glass (a measure of how much the light bends).
In glasses, the lenses are carefully designed to refract light in a specific way:
* Concave lenses (thinner in the middle) diverge light, spreading it out, which helps people with nearsightedness (difficulty seeing distant objects).
* Convex lenses (thicker in the middle) converge light, focusing it, which helps people with farsightedness (difficulty seeing close objects).
So, the next time you put on your glasses, remember that the light isn't just passing through; it's being carefully manipulated to help you see the world more clearly!
