Propagation of Light, Reflection, and Refraction General Behavior of Light

Reflection

The bouncing of light when it reaches a reflective surface or boundary between two media.

Wave Model of Reflection

Light waves reflect off surfaces at the same angle they hit, following the Law of Reflection.

Particle Model of Reflection

Photons bounce off surfaces like tiny balls, reflecting at equal angles.

Refraction

The bending of light as it passes from one medium to another with a different density.

Wave Model of Refraction

Light waves change speed when entering a different medium, causing them to bend.

Particle Model of Refraction

Photons change direction due to speed changes when moving between different media.

Law of Reflection

The angle of incidence is equal to the angle of reflection.

Angle of Incidence

The angle between the incident ray and the normal line.

Angle of Reflection

The angle between the reflected ray and the normal line.

Specular Reflection

Reflection that occurs when parallel rays of light hit a smooth surface and are reflected uniformly, producing clear images like in mirrors.

Diffuse Reflection

Reflection that occurs when parallel beams of light hit uneven or rough surfaces, scattering light in many directions.

Laws of Refraction

Rules explaining how light bends when moving between different media.

Light Entering a Denser Medium

Light bends toward the normal because it slows down.

Light Entering a Less Dense Medium

Light bends away from the normal because it speeds up.

Index of Refraction (n)

The ratio of the speed of light in a vacuum (c) to the speed of light in a material (v): n = c/v. The refractive index is always greater than 1.

Dual Nature of Light

The concept that light exhibits both wave-like and particle-like properties, known as wave-particle duality.

Particle Model of Light (Isaac Newton)

Light consists of particles called corpuscles that travel in straight lines.

Isaac Newton

Proposed the particle model of light, explaining reflection as photons bouncing off surfaces and refraction as photons changing direction at boundaries.

Wave Model of Light (Christiaan Huygens)

Light is a wave that travels through a medium called aether.

Christiaan Huygens

Proposed the wave model of light, explaining reflection as light waves bouncing back and refraction as waves changing speed and direction.

Photon Energy

The energy carried by a photon, which is directly proportional to its frequency: E = hν.

Planck’s Constant (h)

A constant used in the equation relating photon energy and frequency.

Red Light in Photographic Dark Rooms

Red light has low frequency and low energy, so it does not affect photographic paper, allowing safe handling of materials.

Ultraviolet (UV) Light

Light with higher frequency and energy than visible light that can penetrate the skin and damage cells, causing sunburn.

Perception of Colors

The process where eyes detect different frequencies of visible light as different colors.

Red Light

Visible light with lower frequency and lower energy.

Blue Light

Visible light with higher frequency and higher energy.

Photoreceptor Cells

Cells in the retina that are stimulated by photons of different energies, allowing humans to perceive a wide spectrum of colors.