Electromagnetic Radiation
Wave Properties
Light, X-rays, gamma rays and radio waves are all examples of electromagnetic (EM) radiation. Waves can be described by five properties:
Light, X-rays, gamma rays and radio waves are all examples of electromagnetic (EM) radiation. Waves can be described by five properties:
1) Amplitude 2) Wavelength 3) Frequency 4) Speed 5) Energy |
The height of the wave.
Measured from the resting line to the top of a crest. Measured in meters A crest and trough of a wave
Measured from the beginning of a crest to the end of the next successive trough. Measured in meters Symbol (λ) How many times the wave oscillates up and down each second.
Measured in Hertz (Hz), or cycles per second. Symbol (f) Electromagnetic radiation all moves at the same constant speed: 3 x108 m/s, or 300,000,000 m/s.
Symbol (v) Amount of work done by the wave (J) Symbol (E) |
The frequency and the wavelength are inversely proportional. If the frequency goes up (more waves per second), the wavelength goes down (waves become shorter). The equation that relates these two properties is:
v=λf
Example: FM radio waves are electromagnetic waves. A certain radio station broadcasts at 101.1 MHz (101,000,000 Hz). What is the wavelength of this radio wave? Remember, all EM radiation travels at 3 x108 m/s.
Electromagnetic Radiation
Electromagnetic radiation has been categorized into 7 types:
Electromagnetic radiation has been categorized into 7 types:
Type of Wave
Radio Microwave Infrared (IR) Visible Light Ultraviolet (UV) X-rays Gamma Rays |
Properties
Lowest energy, lowest frequency, longest wavelength Heat radiation Only type that can be seen Highest energy, highest frequency, shortest wavelength |
Examples
TV and radio communication Makes water move faster, cell phone communication Ovens, Electric heaters Laser, Illumination Killing bacteria, Tanning X-rays can penetrate skin, but not bone Small doses used in radiation therapy for cancers |
Here is another depiction of the electromagnetic spectrum. Notice that there are no set determinations between the types of waves. Rather, radio blends into microwave, microwave blends into IR, etc.
The Visible Spectrum
The visible spectrum of the electromagnetic spectrum is quite small in comparison to the rest of the electromagnetic spectrum. Light is produced by a luminous body, and visible light has 7 natural colors: red, orange, yellow, green, blue, indigo and violet. Red has the longest wavelength, lowest energy and lowest frequency. Remember the acronym- ROYGBIV
The visible spectrum of the electromagnetic spectrum is quite small in comparison to the rest of the electromagnetic spectrum. Light is produced by a luminous body, and visible light has 7 natural colors: red, orange, yellow, green, blue, indigo and violet. Red has the longest wavelength, lowest energy and lowest frequency. Remember the acronym- ROYGBIV