Refraction and Transmission of Light

Light

Refraction

• The bending of light as it passes from one medium to another
• Occurs due to change in speed of light as it enters a new medium
• Snell's Law describes the relationship between the angles of incidence and refraction
  • n1 sin(θ1) = n2 sin(θ2)
• Examples:
  • Light passing from air into water or glass
  • Total internal reflection (critical angle)

Transmission

• The passage of light through a medium with little or no scattering
• Depends on the properties of the medium and the wavelength of light
• Examples:
  • Visible light passing through air or glass
  • Infrared radiation passing through certain plastics

Emission

• The process by which atoms or molecules release energy as photons
• Types of emission:
  • Thermal emission (blackbody radiation)
  • Luminescence (fluorescence, phosphorescence)
  • Electroluminescence (LEDs)
• Examples:
  • Incandescent light bulbs
  • Fireflies (bioluminescence)

Absorption

• The process by which atoms or molecules absorb energy from photons
• Absorption spectra show the wavelengths of light absorbed by a substance
• Types of absorption:
  • Electronic absorption (electrons transition to higher energy levels)
  • Vibrational absorption (molecules absorb energy to vibrate)
• Examples:
  • Chlorophyll absorbing blue and red light in plants
  • Atmospheric gases absorbing infrared radiation

Reflection

• The change in direction of light when it hits a surface
• Types of reflection:
  • Specular reflection (mirror-like reflection)
  • Diffuse reflection (scattered reflection)
• Examples:
  • Mirrors and other reflective surfaces
  • Retroreflectors (reflect light back to its source)

Light

Refraction

• Light bends when it passes from one medium to another due to a change in its speed.
• This occurs because light travels at different speeds in different mediums.
• Snell's Law describes the relationship between the angles of incidence and refraction: n1 sin(θ1) = n2 sin(θ2).
• Refraction occurs when light passes from air into water or glass, and is responsible for total internal reflection at a critical angle.

Transmission

• Transmission occurs when light passes through a medium with little or no scattering.
• The passage of light depends on the properties of the medium and the wavelength of light.
• Visible light passes through air or glass with little scattering, while infrared radiation can pass through certain plastics.
• Transmission is affected by the wavelength of light and the properties of the medium.

Emission

• Emission is the process by which atoms or molecules release energy as photons.
• There are three types of emission: thermal emission, luminescence, and electroluminescence.
• Thermal emission, also known as blackbody radiation, occurs when objects emit light due to their temperature.
• Luminescence includes fluorescence and phosphorescence, and occurs when energy is absorbed and then released as light.
• Electroluminescence occurs when an electric current passes through a material, causing it to emit light, as seen in LEDs.
• Examples of emission include incandescent light bulbs, fireflies, and LEDs.

Absorption

• Absorption is the process by which atoms or molecules absorb energy from photons.
• Absorption spectra show the wavelengths of light absorbed by a substance.
• There are two types of absorption: electronic absorption and vibrational absorption.
• Electronic absorption occurs when electrons transition to higher energy levels, while vibrational absorption occurs when molecules absorb energy to vibrate.
• Examples of absorption include chlorophyll absorbing blue and red light in plants, and atmospheric gases absorbing infrared radiation.

Reflection

• Reflection occurs when light changes direction after hitting a surface.
• There are two types of reflection: specular reflection and diffuse reflection.
• Specular reflection occurs when light is reflected in a mirror-like fashion, while diffuse reflection occurs when light is scattered in different directions.
• Examples of reflection include mirrors, retroreflectors, and other reflective surfaces.