# Light interactions.

## Presentation on theme: "Light interactions."— Presentation transcript:

Light interactions

Review: Light – EM waves produced by the vibration of particles
Visible light – part of the EM spectrum that we see and that interacts with materials around us Transmission: any transfer of energy through matter or space Light will transfer through a medium or empty space

Materials Transparent Translucent Opaque
Light passes through the object completely Examples: plastic wrap, windows Translucent Light passes through the object somewhat Examples: frosted glass, wax paper Opaque Light does not pass through the object Examples: books, aluminum foil

Reflection and Refraction
Processes where light is manipulated, changed

Reflection Light hits and object and bounces back to the viewer
The light bounces back at the same angle it hit the object Examples: mirrors, some windows Smooth surfaces create regular reflections which means that the light reflects in one direction Rough surfaces create diffuse reflections which mean that the light reflects in different direction. Diagram:

Refraction Diagram Light hits an object and travels through it BUT
It will travel through the object at a different angle than how it hit Creates an optical illusion. Objects may be closer or further away from where you think they are. Ex. A fish in the water. When white light is refracted, you can see the entire visible spectrum. Examples: light traveling from air to water, prism Diagram

Absorption Light is taken in by an object Example:
when a beam of light shines through the air, particles in the air absorb some of the energy from the light. AS a result, the beam of light becomes dim.

Scattering Light is broken up and travels through a medium in smaller particles Example: Beam of light scatters because of air particles, allowing you to see things that are outside of the beam.

Diffraction Bending of waves around barriers or through openings
Depends on it wavelength and the size of the barrier/opening Wavelength of visible light is very small – so it cannot bend very much unless it passes through a narrow opening, sharp edge Light waves cannot diffract around large obstacles (buildings). Thus, you can’t see around corners