Glossary
Electromagnetic Spectrum
The full range of all possible frequencies of electromagnetic radiation, ordered by wavelength or frequency.
Example:
From radio signals to medical X-rays, all are part of the vast electromagnetic spectrum.
Electromagnetic Waves
Waves composed of oscillating electric and magnetic fields that propagate through space, carrying energy and momentum.
Example:
When you use your phone, it sends and receives signals via electromagnetic waves that travel through the air.
Gamma Rays
The highest-energy electromagnetic waves with the shortest wavelengths, produced by radioactive decay and nuclear processes.
Example:
Cosmic events like supernovae can produce powerful bursts of gamma rays that travel across the universe.
Infrared
Electromagnetic waves with wavelengths longer than visible light but shorter than microwaves, often associated with heat.
Example:
Night vision goggles detect infrared radiation emitted by warm objects, allowing you to see in the dark.
Light
A general term that can refer to the visible portion of the electromagnetic spectrum or, more broadly, to all forms of electromagnetic radiation.
Example:
The speed of light in a vacuum is a fundamental constant in physics.
Medium
A substance or material through which waves can travel. Electromagnetic waves do not require a medium for propagation.
Example:
Sound waves need a medium like air or water to travel, but light from the sun can reach us through the emptiness of space.
Microwaves
Electromagnetic waves with wavelengths shorter than radio waves but longer than infrared, commonly used in ovens and radar systems.
Example:
A microwave oven heats food by causing water molecules to vibrate using these specific electromagnetic waves.
Oscillating Electric and Magnetic Fields
The fundamental components of an electromagnetic wave, where the electric and magnetic fields vibrate sinusoidally and are mutually perpendicular.
Example:
A radio antenna generates oscillating electric and magnetic fields that then launch into space as a radio wave.
Perpendicular Relationship
Describes how the electric field, magnetic field, and direction of propagation in an electromagnetic wave are all at right angles to each other.
Example:
Imagine a flashlight beam: the light travels forward, while its electric and magnetic fields vibrate in planes perpendicular to each other and to the beam's direction.
Plane Waves
A simplified model of a wave where the wavefronts (surfaces of constant phase) are flat and parallel, often used to analyze electromagnetic wave behavior.
Example:
When considering light from a very distant source, like the sun, it can often be approximated as a plane wave when it reaches Earth.
Radio Waves
Electromagnetic waves with the longest wavelengths and lowest frequencies in the electromagnetic spectrum, used for broadcasting and communication.
Example:
Your car's stereo receives radio waves to play your favorite music station.
Transverse Waves
Waves in which the oscillations of the medium (or fields, in the case of EM waves) are perpendicular to the direction of wave propagation.
Example:
Shaking a rope up and down to create a wave that moves horizontally demonstrates a transverse wave, similar to how light propagates.
Ultraviolet
Electromagnetic waves with wavelengths shorter than visible light but longer than X-rays, known for causing sunburns and used in sterilization.
Example:
Sunscreen protects your skin from harmful ultraviolet radiation from the sun.
Vacuum
A space devoid of matter. Electromagnetic waves can travel through a vacuum, unlike mechanical waves.
Example:
The light from distant stars reaches Earth by traveling across the vast vacuum of interstellar space.
Visible Light
The portion of the electromagnetic spectrum that is detectable by the human eye, ranging from red (longest wavelength) to violet (shortest wavelength).
Example:
A rainbow displays the full range of colors within the visible light spectrum.
Visible Light Colors
The specific colors that make up the visible light spectrum, ordered by decreasing wavelength: Red, Orange, Yellow, Green, Blue, Indigo, and Violet (ROY G. BIV).
Example:
When sunlight passes through a prism, it separates into the distinct visible light colors.
Wavelength
The spatial period of a wave, which is the distance over which the wave's shape repeats. It is a key characteristic used to categorize electromagnetic waves.
Example:
Different colors of visible light, like red and blue, are distinguished by their distinct wavelengths.
X-rays
High-energy electromagnetic waves with very short wavelengths, capable of penetrating soft tissues and widely used in medical imaging.
Example:
Doctors use X-rays to view bones and detect fractures inside the body.