Why does light bend when it enters water or glass?
Quick Answer
Light slows down in materials like water and glass, so its path changes direction at the boundary. That bending is called refraction.
The Full Story
Light travels fastest in a vacuum, but it slows down when it passes through matter. If a light beam hits water or glass at an angle, one side of the wavefront slows first, causing the beam to bend. This effect is why a straw looks bent in a glass of water and why lenses can focus light. Refraction is described by Snell’s law, and it is essential in cameras, eyeglasses, microscopes, and the human eye. The speed change is not usually dramatic, but it is enough to alter the path of light.
Key Facts
YouTube Angle
Suggested video title for this topic:
"Why does a spoon look broken in water?"
Was this answer helpful?
Tap a reaction — it helps us pick what to cover next.