Refraction and Lenses

Refraction of light, convex and concave lenses, and how the human eye works. Class 7 Science with quiz.

Class 7 ScienceClass 7 / Grade 7Ages 9–12
Lesson
🔍 Refraction and Lenses
Refraction — light bends when it changes mediumAIR (less dense)GLASS (more dense)incidentrefracted (bends toward normal)Light slows down in denser media → bends!

Refraction is the bending of light when it passes from one medium to another — for example from air into glass or water. Light bends because it travels at different speeds in different materials. In air it travels fastest; in glass or water it slows down. When light enters a denser medium at an angle, the slowing causes it to bend toward the normal. When it exits back into a less dense medium, it bends away from the normal. A straw in a glass of water appears bent — this is refraction in action.

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