Reflection and Refraction

Reflection It occurs when an energy wave strikes an object and bounces off. Light and sound can be reflected. Echos Mirrors

Reflection When the surface is smooth, the reflection is clear. When the surface is rough, the reflection is uneven or fuzzy. The wave is scattered in many directions. The reflection always bounces off at an equal angle.

Reflection Smooth Mirror Rough Mirror

Reflection Angles Imagine a light ray hitting a mirror. Normal = 90 degree angle from the object reflecting the light Angle of Incidence- the angle formed between the energy wave and the normal line (i)

Reflection Angles Angle of Reflection- the angle formed between the reflected energy wave and the normal line (r) On a flat surface like a mirror, i=r So if i=60 degrees then r will also = 60 degrees.

Refraction The bending of a wave as it passes from one medium to another. Must remember that waves travel with different speeds in different mediums. Try grabbing a fish in an aquarium!

Refraction Let’s look at light moving from air to water. A line perpendicular to the water’s surface is the normal. As light passes from air to water, it bends closer to the normal. Less dense to more dense bends toward the normal Normal

Refraction Lets look at light moving out of water into air. The light bends away from the normal as it moves in this manner. (more dense water to less dense air.) This is why the fish is in a different place than what you see! Normal

Color A prism uses the property of waves to split white light into the rainbow. The prism refracts the white light into the colors because of the differing wavelengths.

Rainbows White light separates into different colors (wavelengths) on entering the raindrop because red light is refracted by a lesser angle than blue light. On leaving the raindrop, the red rays have turned through a smaller angle than the blue rays, producing a rainbow.

Wave Speed Waves travel at different speeds. Light is faster than sound. Light travels at 300 million meters per second. Sound travels at about 340 meters per second.

Wave Speed The closer together particles are in the medium, the faster a mechanical wave will travel. So sound travels faster in solids than in liquids, and faster in liquids than in air.