Waves: Introduction, Types, and Properties

This set covers vocabulary and key concepts regarding wave types, properties, sound mechanics, and electromagnetic radiation as presented in the lecture notes.

Wave

A transfer of energy through a medium from one point to another; a disturbance that carries energy from place to place without carrying matter.

Medium

The substance or material through which a wave moves, carrying the energy from one place to another.

Transverse Wave

A wave in which the medium moves perpendicular (at right angles) to the direction of the wave motion.

Longitudinal Wave

A wave in which the medium moves parallel (back and forth) in the same direction as the wave motion.

Pulse

A single vibration moving through a medium.

Electromagnetic Waves (EM waves)

Waves that do not need a medium to move and can travel through space; they consist of varying electric and magnetic fields oscillating at right angles to each other.

Mechanical Waves

Waves that must have a medium in order to move.

Crest

The location of maximum upward displacement in a transverse wave.

Trough

The location of maximum downward displacement in a transverse wave.

Amplitude

The measurement of maximum displacement from the position of rest (equilibrium).

Wavelength ($\lambda$)

The distance of one complete wave cycle, such as the distance from crest to crest or trough to trough, measured in meters ($m$).

Compressions

Areas in a longitudinal wave where the particles of the medium are close together, representing maximum displacement.

Rarefactions

Areas in a longitudinal wave where the particles of the medium are spread apart.

Frequency ($f$)

How many waves go past a point in one second; measured in hertz ($Hz$).

Period ($T$)

The time taken for one full wave to pass a certain point, measured in seconds ($s$).

Wave Speed (Velocity)

Depends on the medium and is calculated using the formula $\text{Wave Speed} = \text{Wavelength} \times \text{Frequency}$ ($v = \lambda \times f$).

Sound Waves

Mechanical longitudinal pressure waves caused by vibrations that create constant variations of pressure in the air.

Speed of Sound

In air at sea level and $21^\circ\text{C}$, it is approximately $344\,m \cdot s^{-1}$; it travels faster in solids than in liquids or gases.

Pitch

The quality of sound determined by the frequency of the sound wave.

Loudness

The quality of sound determined by the amplitude of the sound wave.

Infrasound

Any sound with a frequency below $20\,Hz$.

Ultrasound

Any sound with a frequency above $20,000\,Hz$ ($20\,kHz$).

Principle of Superposition

States that the effect of different pulses meeting in the same medium is the sum of their individual effects.

Constructive Interference

Takes place when two pulses meet to create a larger pulse, where the resulting amplitude is the sum of the two initial amplitudes.

Destructive Interference

Takes place when two pulses meet and cancel each other or create a smaller pulse.

Photon

A quantum or energy packet of light; a particle of light.

Wave-Particle Duality

The theory that light and EM radiation show both wave-like and particle-like properties depending on the experiment performed.

Planck's Constant ($h$)

A physical constant used in the formula $E = hf$, with a value of $6.626 \times 10^{-34}\,J \cdot s$.

Ionizing Radiation

High-energy radiation such as ultraviolet radiation, X-rays, and gamma rays that can break molecular bonds and create ions.

SONAR

Stands for Sound Navigation And Ranging; a system that uses reflected sound waves to determine the distance to the seabed.

Echolocation

The use of reflected ultrasound waves by animals like bats and dolphins to form a picture of their surroundings.