Electromagnetic Radiation

Radio Waves

Radio waves: at the lowest energy range of the electromagnetic spectrum, with frequencies as high as 300 gigahertz (GHz) to as low as 30 hertz.
At 300 GHz, the corresponding wavelength is 1 mm; at 30 Hz the corresponding wavelength is 10,000 km.
Radio waves are used primarily for communications including voice, data and entertainment media.

Microwaves

Microwaves: fall in the range of the electromagnetic spectrum between radio and IR.
With frequencies between 300 MHz and 300 GHz, they are a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter.
Microwaves are used for high-bandwidth communications, radar and as a heat source for microwave ovens and industrial applications.

Infrared (IR): in the range of the electromagnetic spectrum between microwaves and visible light.
IR wavelengths extend from the red edge of the visible spectrum at 700 nanometers (frequency 430 THz), to 1 millimeter (300 GHz)
IR light is invisible to human eyes, but we can feel it as heat if the intensity is sufficient (most of the thermal radiation emitted by objects near room temperature is infrared).
Night-vision devices using active near-infrared illumination allow people or animals to be observed without the observer being detected.

Visible light is found in the middle of the electromagnetic spectrum, between IR and UV.
It has frequencies of about 400 THz to 800 THz and wavelengths of about 740 nm (0.00003 inches, red) to 380 nm (0.000015 inches, violet).
Visible light: the wavelengths that are visible to most human eyes.

Ultraviolet light is in the range of the electromagnetic spectrum between visible light and X-rays.
It has frequencies of about 8×1014 to 3×1016 Hz and wavelengths of about 380 nm (.000015 inches) to about 10 nm (0.0000004 inches).
UV light: a component of sunlight; however, it is invisible to the human eye.
It has numerous medical and industrial applications, but it can damage living tissue.

X-rays are roughly classified into two types: soft X-rays and hard X-rays
- Hard x-rays: the highest energy x-rays
  - Hard X-rays with wavelengths below 0.1 nm down to 10 pm, occupy approximately very close region of the electromagnetic spectrum to gamma rays.
- Soft x-rays: the lower energy x-rays
  - Soft X-rays have frequencies of about 3×1016 to about 1018 Hz and wavelengths of about 10 nm (4×10−7 inches) to about 0.100 nanometers (nm), or 4×10−8 inches.

Gamma-rays: in the range of the spectrum above soft X-rays.
Gamma-rays have frequencies greater than about 1018 Hz and wavelengths of less than 10 pm.
Gamma radiation causes damage to living tissue, which makes it useful for killing cancer cells when applied in carefully measured doses to small regions.
Uncontrolled exposure, though, is extremely dangerous to humans.

Radio waves: at the lowest energy range of the electromagnetic spectrum, with frequencies as high as 300 gigahertz (GHz) to as low as 30 hertz.
At 300 GHz, the corresponding wavelength is 1 mm; at 30 Hz the corresponding wavelength is 10,000 km.
Radio waves are used primarily for communications including voice, data and entertainment media.

Microwaves: fall in the range of the electromagnetic spectrum between radio and IR.
With frequencies between 300 MHz and 300 GHz, they are a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter.
Microwaves are used for high-bandwidth communications, radar and as a heat source for microwave ovens and industrial applications.

Infrared (IR): in the range of the electromagnetic spectrum between microwaves and visible light.
IR wavelengths extend from the red edge of the visible spectrum at 700 nanometers (frequency 430 THz), to 1 millimeter (300 GHz)
IR light is invisible to human eyes, but we can feel it as heat if the intensity is sufficient (most of the thermal radiation emitted by objects near room temperature is infrared).
Night-vision devices using active near-infrared illumination allow people or animals to be observed without the observer being detected.

Visible light is found in the middle of the electromagnetic spectrum, between IR and UV.
It has frequencies of about 400 THz to 800 THz and wavelengths of about 740 nm (0.00003 inches, red) to 380 nm (0.000015 inches, violet).
Visible light: the wavelengths that are visible to most human eyes.

Ultraviolet light is in the range of the electromagnetic spectrum between visible light and X-rays.
It has frequencies of about 8×1014 to 3×1016 Hz and wavelengths of about 380 nm (.000015 inches) to about 10 nm (0.0000004 inches).
UV light: a component of sunlight; however, it is invisible to the human eye.
It has numerous medical and industrial applications, but it can damage living tissue.

X-rays are roughly classified into two types: soft X-rays and hard X-rays
- Hard x-rays: the highest energy x-rays
  - Hard X-rays with wavelengths below 0.1 nm down to 10 pm, occupy approximately very close region of the electromagnetic spectrum to gamma rays.
- Soft x-rays: the lower energy x-rays
  - Soft X-rays have frequencies of about 3×1016 to about 1018 Hz and wavelengths of about 10 nm (4×10−7 inches) to about 0.100 nanometers (nm), or 4×10−8 inches.

Gamma-rays: in the range of the spectrum above soft X-rays.
Gamma-rays have frequencies greater than about 1018 Hz and wavelengths of less than 10 pm.
Gamma radiation causes damage to living tissue, which makes it useful for killing cancer cells when applied in carefully measured doses to small regions.
Uncontrolled exposure, though, is extremely dangerous to humans.