Light Transmission and Interaction

Study Notes

Light is made up of individual units called photons, which act as both particles and waves.
The electromagnetic radiation spectrum includes different forms of light, such as:
- Microwaves, radio waves, and visible light (middle of the spectrum)
- Ultraviolet light, x-rays, and gamma rays (high frequencies, high energy)
- Infrared light, microwaves, and radio waves (low frequencies, low energy)
When light interacts with objects, it can be:
- Reflected (bounced off, like a particle)
- Absorbed (energy taken in by molecules, transformed into thermal energy)
- Transmitted (passes through objects, like a wave)

Objects with high reflective properties (e.g., glass, mirrors, shiny surfaces) reflect most of the light that hits them.
Opaque objects absorb light, converting it to thermal energy.
Light absorption and reflection are responsible for our perception of color:
- White light (all frequencies) hits an object, and the reflected color is what we see.

Light transmission through transparent materials (e.g., glass, water, plastic) allows light to pass through with little change.
In the atmosphere, about 30% of sunlight is reflected, while the rest is absorbed or transmitted to the Earth's surface.
Scattering and refraction occur when light interacts with the atmosphere:
- Scattering: light hits atoms and is transmitted in all directions (making the sky appear blue)
- Refraction: light bends as it changes speed through a material (creating rainbows)

Waves are disturbances in a medium that travel through the medium in an organized way.
Waves can propagate energy, momentum, and/or information, but not matter.
Types of waves include:
- Light waves (photons, particles of light)
- Sound waves (require a medium, like air or water)
- Kinetic waves (transfer energy through a medium, like water)

Wave transmission is the movement of a wave through a medium.
The type of wave and medium can change the wave's energy, wavelength, and frequency.
Energy loss occurs when waves change medium or type.
Waves can be scattered or refracted as they transmit through a medium.