General Science: Understanding & Using Light and Sound

Comprehensive vocabulary flashcards covering the history, properties, and comparison of light and sound as presented in the General Science lecture.

Ibn al-Haytham (Alhazen)

Known as the "Father of Optics," he proved that light travels from objects into our eyes and explained reflection and refraction using the scientific method.

Isaac Newton

Scientist who demonstrated that white light is composed of different colors using a prism and proposed the corpuscular (particle) theory of light.

Albert Einstein

Explained the photoelectric effect, showing light behaves as particles called photons, leading to the concept of wave-particle duality.

Pythagoras

Ancient Greek philosopher who discovered that the pitch of a musical note depends on the length of a vibrating string.

Ernst Chladni

Scientist who visualized sound vibrations using sand on metal plates, creating patterns now named after him.

Light

A form of electromagnetic energy that travels as electromagnetic waves and does not require a material medium to travel.

Rectilinear Propagation

The property of light that describes its travel in straight lines within a uniform medium.

Speed of Light in a vacuum

The fastest known phenomenon in nature, measured at approximately $300,000\,km/s$ or $3.0 \times 10^8\,m/s$.

Regular (Specular) Reflection

Reflection that occurs on smooth surfaces, producing a clear image.

Diffuse Reflection

Reflection that occurs on rough surfaces and produces no clear image.

Laws of Reflection

Rules stating that the angle of incidence equals the angle of reflection, and the incident ray, reflected ray, and normal line lie in the same plane.

Refraction

The bending of light as it passes from one medium to another due to a change in its speed.

Snell's Law

The formula used to describe refraction: $n_1 \sin(\theta_1) = n_2 \sin(\theta_2)$, where $n$ is the refractive index and $\theta$ is the angle with the normal.

Dispersion

The separation of white light into its different colors, often occurring when passing through a prism.

Diffraction (Light)

The bending or spreading of light as it passes around obstacles or through narrow openings.

Constructive Interference

Occurs when waves overlap and reinforce each other, producing bright bands in light or louder sounds.

Destructive Interference

Occurs when waves overlap and cancel each other out, producing dark bands in light or quieter sounds/silence.

Polarization

The restriction of light vibrations to a single plane, providing evidence that light is a transverse wave.

Transparent

Materials that allow almost all light to pass through clearly, such as clear glass or clean water.

Translucent

Materials that allow some light through but scatter it, such as frosted glass or wax paper.

Opaque

Materials that do not allow light to pass through, such as wood, brick, or metal.

Polarization

The phenomenon where light changes direction after interacting with particles, explaining why the sky appears blue and sunsets appear red.

Wave-Particle Duality

The concept that light exhibits both wave-like properties (refraction, interference) and particle-like properties (photons).

Sound

A form of mechanical energy produced by vibrations that travels through a medium as a longitudinal mechanical wave.

Longitudinal Wave

A wave where the particles of the medium vibrate parallel to the direction of wave travel.

Compression

A region in a longitudinal wave where particles are crowded together, resulting in high pressure and high density.

Rarefaction

A region in a longitudinal wave where particles are spread apart, resulting in low pressure and low density.

Speed of Sound in Air ($20^{\circ}C$)

Approximately $343\,m/s$; it is slower than the speed of sound in liquids or solids.

SONAR

An acronym for Sound Navigation and Ranging, which uses sound pulses to detect objects under water.

Frequency

The number of complete vibrations or cycles produced per second, measured in Hertz ($Hz$), which determines pitch.

Human Hearing Range

The range of sound frequencies audible to humans, typically from $20\,Hz$ to $20,000\,Hz$.

Infrasound

Sound with a frequency below $20\,Hz$.

Ultrasound

Sound with a frequency above $20,000\,Hz$.

Amplitude (Sound)

The maximum displacement of particles from equilibrium, which determines the loudness of a sound.

Decibel (dB) scale

The scale used to measure the intensity or loudness of sound, with a rock concert reaching approximately $110\,dB$.

Timbre (Quality of Sound)

The character of a sound that allows us to distinguish between different sources even if they have the same pitch and loudness.

Echo

A reflected sound that is heard separately from the original sound.

Reverberation

The persistence of sound in an enclosed space after the original source has stopped.

Absorption (Sound)

Occurs when soft, porous materials take in sound energy instead of reflecting it, reducing noise.