How Does Light Travel?. UNIT 4, LESSON 3 4-5.3. LIGHT. Light travels at a very fast speed, but travels more slowly through matter. Light travels in straight lines. Light cannot bend or turn corners, so shadows form when you block light from a source.
How Does Light Travel? UNIT 4, LESSON 3 4-5.3
LIGHT • Light travels at a very fast speed, but travels more slowly through matter. • Light travels in straight lines. • Light cannot bend or turn corners, so shadows form when you block light from a source. • The light can’t bend or turn to go around the object blocking the light.
Reflection • Reflection occurs when light bounces, or reflects, from a surface. • When you look at a mirror, you see your reflection because most of the light that hits the mirror bounces back to your eyes. • When you look in the water of a quiet lake, the reflected image is clear. But if the water is rippled, the reflected image isn’t clear. • Why the difference? • The water surface of the quiet lake is smooth, so most of the light is reflected in the same direction. • The water surface of the rippled lake is bumpy, so light is reflected in different directions. • Your eyes see a clear image when light is reflected in the same direction. When light is reflected in different directions, your eyes see a blurry image.
Refraction • When light moves at an angle from one material to another, it bends, or refracts. This bending of light is called refraction. • An example of this is when a pencil looks broken when placed in a glass of water. • Light refracts as it moves from the air to the water. As a result, the pencil looks like it is broken. • Light travels at different speeds in different materials. • The more tightly the particles in matter are packed, the slower light moves through the matter. • Particles in a liquid are closer together than particles in a gas, so light moves slower through the water than through the air. • Light moves slower through a solid than liquids and the gases.
Absorption • Not all materials reflect or refract light. • Some materials absorb light. Absorption occurs when an object takes in light. • Most objects absorb only some wavelengths of light, and they reflect other wavelengths. • An object’s color is determined by which colors it reflects and which colors it absorbs. • An apple appears red because it reflects red light and absorbs the other colors of light. • A banana reflects yellow light and absorbs other colors. • White light is made up of all the colors of light. Something white reflects all colors of light. • Something black absorbs all colors of light.