(λ)=400 nm
Single Wavelength
(λ)=700 nm
(waves of particles)
EMR as a Wave
Electromagnetic waves contain both an electric field and a magnetic field that oscillate while traveling at the speed of light. Each field is an area of space
in which electrical and magnetic energy is stored and is measured in joules (J). Changes to the electric or magnetic fields produces an EMR wave that travels through space.
Electromagnetic radiation is classified by the Electromagnetic Spectrum (EMS) consisting of seven class types: radio waves, microwaves, infrared, visible light,
ultraviolet, X-rays and gamma rays. A specific range of wavelengths or energy levels define each class type of EMS.
The correlation between wavelength and wave frequency is an equation which holds true for all electromagnetic waves:
(λ) is the Greek letter lambda used to express a single wavelength (or cycle or period) of EMR (∿) with a length expressed in meters.
c, is the speed of light, in meters per second: 299,792,458 m/s.
f, is the wave frequency in cycles per second, expressed in Hertz (Hz).
If 550 nm is the midpoint of the visible light spectrum,
what is the frequency at that point?
EMR as a Particle
Electromagnetic energy is composed of fundamental particles called photons (or quanta) that have characteristics of both particles and waves. Photons are discrete packets of
energy that make up the entire EMS spectrum where energy levels depend on the wave frequency. Low-energy photons make up radio waves,
while high-energy photons make up X-rays and gamma-rays. A specific energy level also defines each class type of EMS.
A correlation exists between the energy of a photon and its wave frequency. The following equation also holds true for all electromagnetic waves:
E is the energy of one photon or light particle. E is expressed in units of (eV), electronVolt.
h is Planck’s constant = 6.6260715 x 10-34 (Js) Joule seconds.
f is the frequency of a photon expressed in Hertz (Hz).
Using (λ) = 550 nm with a frequency of 545,077,196 MHz,
what is the energy of a single photon using
E = h x f ?
Answer: 6.6260715 x 10-34 Js x 545,077,196 x 106 MHz = 3.612 x 10-19 Joules
EMR regions with a typical wavelength value
...from low energy EMR up to cosmic radiation...
Radio Frequency (λ) = 100 m
Radio waves are a type of electromagnetic radiation created by an alternating current (AC) that moves through conductors such as wires or antennas
that in turn generate an electromagnetic field (EM). The EM field is a combination of an electric field and a magnetic field that oscillate while
traveling at the speed of light. Radio frequency waves, also called RF, have the lowest frequencies and longest wavelengths in the EMS spectrum.
Microwave (λ) = 10 mm
Microwaves occupy a region of the EMS with wavelengths ranging from 1 mm to 1 meter making them
short-wavelength radio waves. Microwave ovens radiate at a frequency of 2.45 GHz, with (λ) = 122 mm, creating heat from
molecular friction via a transfer of energy. The wave properties of microwaves make them well suited for use in satellite
communication and radar systems.
Infrared (λ) = 10 μm
The invisible infrared region covers wavelengths from 700 nm up to 1 mm. IR is also known as thermal radiation and is
naturally produced by solar radiation and fire. Every object, both hot and cold, gives off heat in the form of IR. IR has a
lower energy level and a longer wavelength than the EMR that produces visible light.
Visible Light (λ) = 550 nm
The visible light spectrum is a very narrow band of the electromagnetic spectrum. Visible light is comprised
of the colors of the rainbow: red, orange, yellow, green, blue, indigo, and violet. Different wavelengths correspond to the
different colors, with red having the longest wavelength and violet the shortest. Our eyes detect this specific range of wavelengths that
the brain interprets as colors. When combined together the visible wavelengths appear as white light.
Ultraviolet (λ) = 100 nm
The invisible
ultraviolet region covers wavelengths from 400 nm down to 10 nm. The sun is the major source
of UV radiation that is known for it's harmful UV-B and UV-C sub-regions that are mostly absorbed by the earth's atmosphere.
UV has a higher energy level and a shorter wavelength than the EMR that produces visible light.
X-rays (λ) = 1 nm
X-rays (χ) are a high-energy
form of electromagnetic radiation with wavelengths between 0.01 nm and 10 nm and are
generated when inner-shell electrons transition between energy levels. All EMR, including X-rays, radiate energy as waves and photons.
Their short wavelengths allow them to pass through some materials but not through dense materials such as bones.
X-rays are a high-energy form of ionizing radiation, meaning they can damage living tissue.
Gamma rays (λ) = 1x10-6 nm
Gamma rays (γ) are the highest-energy form of EMR and originate from the nucleus of an atom.
Gamma rays have the smallest wavelengths and are produced by nuclear processes like radioactive decay and supernova explosions.
They are highly penetrating, able to pass through dense materials like lead and can cause damage to living tissue by ionizing atoms.
Originators: Michael Faraday, James Clerk Maxwell, Heinrich Hertz, Ludwig Boltzmann, Max Planck, James Prescott Joule,
Alexander Graham Bell, Guglielmo Marconi.