Light Refraction and Vision Basics

Light Refraction

• Light changes direction when it moves from one material to another. This is called refraction.
• Reflection is when light bounces off a surface. Refraction is when light bends as it passes through a material.

Lenses

• The eye has two lenses, both convex (converging).
• Lenses focus light and allow us to see.
• The point where light rays meet after passing through a lens is called the focal point.

The Eye and Vision

• Light reflects off objects and enters the eye through the pupil.
• The cornea and lens focus the light onto the retina.
• The retina is a light-sensitive layer containing photoreceptors.
• Two types of photoreceptors are rods (movement and dim light) and cones (bright light and color).
• Chemical reactions in the retina convert light into electrical signals.

The Eye and Camera Analogy

• Both eyes and cameras create images.
• Light enters the camera through a pinhole, or pupil in the eye.
• Images are formed on a screen (retina) in both.
• The digital camera's photosensitive grid is called a CCD.

Light Colour

• White light is made of many colors.
• A prism can separate white light into its component colors. This is called dispersion.
• Different colors of light have different wavelengths and frequencies.
• Primary colors of light are red, blue, and green.
• Mixing primary light colors produces secondary colors (cyan, yellow, and magenta).
• Filters transmit some colors and absorb others.
• Black objects absorb all colors of light; white objects reflect all colors.