Physics of Waves: Light, Sound, and Core Concepts

Wave Fundamentals

Wave Definition

A wave is the propagation of a disturbance from point to point, accompanied by the propagation of energy. Its origin is typically the shaking of a body.

Period and Frequency

• Period (T): The time taken for one complete wave cycle, measured in seconds (s).
• Frequency (f): The number of vibrations or cycles per second (f = 1/T), measured in Hertz (Hz).

Wavelength

Wavelength (λ): The distance a wave advances in one period. Different wavelengths correspond to different colors of light and pitches of sound.

Wave Phenomena

Absorption and Attenuation

• Absorption: The process where a medium absorbs wave energy, converting it into other forms of energy (e.g., heat).
• Attenuation: The gradual loss of intensity or amplitude of a wave as it propagates through a medium, often due to energy dissipation or spreading.

Resonance Explained

Resonance: A phenomenon where an external vibrating force causes an object to vibrate at its natural frequency, significantly increasing the amplitude of the initial wave.

Reflection and Refraction

• Reflection: The phenomenon where a wave bounces off a surface or boundary between two media. Reflection can be diffuse (scattered) or specular (mirror-like).
• Refraction: The bending of a wave as it passes from one medium to another, often causing it to converge or diverge.

Light and Color Principles

Color Perception

• Color by Reflection: The color of an opaque object is determined by the wavelengths of light it reflects.
• Color by Transmission: The color of a transparent object is determined by the wavelengths of light it transmits (i.e., the colors it does not absorb).
• Each color corresponds to a specific frequency (or wavelength) of light. For visible light, higher frequencies (shorter wavelengths) are associated with blue/violet, while lower frequencies (longer wavelengths) are associated with red.
• The human eye perceives light within the visible spectrum, typically ranging from approximately 400 nm (violet) to 700 nm (red).

Additive Color Mixing (Light)

The primary colors of light are Red, Green, and Blue (RGB). When mixed in appropriate proportions, these additive primaries produce white light.

Subtractive Color Mixing (Pigments)

Pigments absorb certain wavelengths of light and reflect others, which determines the perceived color. This process is known as subtractive color mixing, commonly seen in paints and printing.

Understanding Sound Waves

Sound Wave Basics

Sound: A mechanical wave that requires a medium for transmission and cannot travel through a vacuum. The human ear can typically perceive sounds with frequencies between 20 Hz and 20,000 Hz. The ear's ability to distinguish separate sounds is about 0.1 seconds.

Sound Intensity and Decibels

Intensity: Indicates the energy transmitted by a sound wave. Higher intensity corresponds to greater perceived volume. Sound intensity is often measured on a nonlinear decibel (dB) scale.

Tone (Pitch)

Tone (Pitch): Refers to the perceived frequency of a sound. Higher frequencies (+ Hz) are perceived as acute (high-pitched), while lower frequencies (- Hz) are perceived as serious (low-pitched).

Timbre

Timbre: The quality of a sound that distinguishes different types of sound production, even when they have the same pitch and loudness. It's determined by the presence and relative intensity of overtones (harmonics) accompanying the fundamental frequency.

Reverberation and Echo

• Reverberation (Reverb): The persistence of sound in a particular space after the original sound is produced, caused by reflections. It occurs when reflections arrive within approximately 0.1 seconds of each other.
• Echo: A distinct reflection of sound that arrives at the listener after the direct sound, typically when the delay is greater than 0.1 seconds.