Refraction is the bending of light as it passes through a medium with a different density, while reflection is the bouncing of light off a surface. Refraction is responsible for phenomena like the bending of a pencil in water, while reflection allows us to see ourselves in a mirror.
The human eye perceives color through specialized cells called cones, which are sensitive to red, green, and blue light. These cones are located in the retina at the back of the eye and send signals to the brain, which then processes the information to create the perception of color.
Convex lenses are thicker in the middle and thinner at the edges, causing light rays to converge and creating a magnifying effect. Concave lenses are thinner in the middle and thicker at the edges, causing light rays to diverge and creating a reduction effect. Convex lenses are commonly used in glasses for farsightedness, while concave lenses are used for nearsightedness.
Light travels in a straight line through a vacuum, but when it enters a medium with a different density, it can be bent or refracted. This is because light travels at different speeds in different mediums, causing it to change direction. Light also gets absorbed or reflected by different materials depending on their properties.
The eye focuses on objects at different distances through a process called accommodation. This is controlled by the ciliary muscles and the lens of the eye, which change shape to adjust the focal length and bring objects into focus on the retina. This allows us to see objects at different distances clearly.