Electric and magnetic fields traveling through empty space with the speed of light
Propagation of Electromagnetic Wave
1. Accelerating charges produce changing electric and magnetic fields
2. Changing electric fields produce magnetic fields
3. Changing magnetic fields produce electric fields
4. This interplay between induced electric and magnetic fields leads to propagating electromagnetic waves
5. Electromagnetic waves can propagate through free space
Wave equation
Relates speed of propagation (v), frequency (f) and wavelength (Λ)
In a vacuum or air, all electromagnetic waves travel at a common speed equal to 3 x 10^8 m/s
Photon
The smallest (quantum) unit of light/electromagnetic energy<|>Photons are generally regarded as particles with zero mass and no electric charge
Wave-particle duality
The amount of energy a photon has can cause it to behave more like a wave, or more like a particle
EM waves
Transverse waves
Amplitude (A)
The height of a wave, usually measured in meters (m)<|>The greater the amplitude (A) of a wave the more energy it carries
Wavelength (λ)
The distance between two consecutive crest or trough, usually measured in meters
Frequency (f)
The number of waves passing a point in a certain time, measured in hertz (Hz)
Speed of light (c)
All electromagnetic waves travel at the same speed of about 3.00 x 10^8 m/s through a vacuum
Wave Equation
v = f λ
EM wave
Wavelength of 4.0 meters in a vacuum space
Frequency of 75,000,000 Hz = 75 MHz
Electromagnetic spectrum
Continuous range of electromagnetic waves arranged in order of frequency or wavelength<|>Divided into regions on the basis of a certain frequency or wavelength interval
Regions of the Electromagnetic Spectrum
Radio waves
Microwaves
Infrared
Visible light
Ultraviolet
X-rays
Gamma rays
Radio waves
Longest wavelengths in the electromagnetic spectrum, ranging from 10^-1 m to 10^4 m<|>Frequency range from 30 kHz to 3000 MHz
Radio waves
Used for long distance communication and navigation
Used for AM radio broadcasting
Used for shortwave broadcasting, tags, public transportation, and electronic payment systems
Used for FM radio broadcasting, ground to aircraft and aircraft to aircraft communication
Used for police radio communication, military aircraft and television transmission, modern mobile phones and global positioning systems
Microwaves
Portion of the electromagnetic spectrum at the higher frequency end of the radio spectrum<|>Frequency range from 300 MHz to 300 GHz, with wavelength corresponding to 10^-3 m to 10^-1 m
Microwaves
Cause water and fat molecules to vibrate, which makes substances hot
Used in mobile phones and Wifi
Used by fixed traffic speed cameras, and for radar used by aircraft, ships and weather forecasters
Microwaves
A portion or "band" found at the higher frequency end of the radio spectrum, but they are commonly distinguished from radio waves because of the technologies used to access them
Microwaves
The microwave region in the EM spectrum lies somewhere from 300 MHz to 300 GHz , with wavelength corresponding to 10−3 m to 10−1 m
James Clerk Maxwell is credited for discovering microwaves in 1864
Microwaves
Cause water and fat molecules to vibrate, which makes the substances hot
Radar
Works by sending out bursts of microwaves, detecting the "echoes" coming back from the objects they hit, and using the time it takes for the echoes to come back to work out how far away the object is
Infrared
Infrared radiations (IR) have a lower frequency than the red part of the visible light, with frequencies ranging from 3x 10 to 4x10^14 Hz and wavelengths ranging from 7.5x 10−7 m to 10−3 m
In 1800, William Herschel conducted an experiment measuring the difference in temperature between the colors in the visible spectrum and discovered infrared light
Uses of infrared
Remote controls for TVs and video recorders
Physiotherapy heat lamps
Short-range communications
CCD chips in digital cameras
Burglar alarm systems
Thermal imaging cameras
Weather forecasting
Visible light
The segment of the electromagnetic spectrum that the human eye can view, with wavelengths from 4x 10−7 m to 8x 10−7 m
Visible light spectrum
The sequence of colors from longest to shortest wavelength: red, orange, yellow, green, blue, indigo, violet (ROYGBIV)
Uses of lasers
Compact Disc & DVD players
Laser printers
Aircraft weapon aiming systems
Ultraviolet (UV) light
Has shorter wavelengths than visible light, with UV-C being the most harmful and UV-A being used for treating skin conditions
Uses of UV light
Getting a sun tan
Detecting forged bank notes
Sterilizing surgical equipment and air
Sterilizing food and drugs
Treating vitamin D deficiency and skin disorders
rays
Have much higher energy and much shorter wavelengths than ultraviolet light, between 0.03 and 3 nanometers
Uses of X-rays
Medical imaging
Airport security checks
Astronomy
Gamma rays
Have the smallest wavelengths and the most energy of any wave in the electromagnetic spectrum, produced by the hottest and most energetic objects in the universe