Ontmeta6. What is sound?
What are sound and frequency?
- “Sound is a longitudinal mechanical wave of any frequency.”
- “Frequency is the number of cycles.”
- “Frequency is the rate at which something occurs or is repeated over a particular period of time or in a given sample.”
- “Frequency is the rate at which a vibration occurs that constitutes a wave, either in a material (as in sound waves), or in an electromagnetic field (as in radio waves and light), usually measured per second.”
- “For an oscillating or varying current, frequency is the number of complete cycles per second in the alternating current direction. The standard unit of frequency is the Hertz, abbreviated Hz. If a current completes one cycle per second, then the frequency is 1 Hz; 60 cycles per second equals 60 Hz (the standard alternating-current utility frequency in some countries).”
- “Frequency describes the number of waves that pass a fixed place in a given amount of time. So if the time it takes for a wave to pass is 1/2 second, the frequency is 2 per second.” 
- “Usually frequency is measured in the hertz unit, named in honor of the 19th-century German physicist Heinrich Rudolf Hertz. The hertz measurement, abbreviated Hz, is the number of waves that pass by per second. For example, an "A" note on a violin string vibrates at about 440 Hz (440 vibrations per second).”
How are frequency and wavelength related?
- “Electromagnetic waves always travel at the same speed (299,792 km per second). This is one of their defining characteristics. In the electromagnetic spectrum there are many different types of waves with varying frequencies and wavelengths. They are all related by one important equation: Any electromagnetic wave's frequency multiplied by its wavelength equals the speed of light.
- FREQUENCY OF OSCILLATION x WAVELENGTH = SPEED OF LIGHT
- The wavelength or frequency of any electromagnetic wave can be determined through measurement. Because frequency times the wavelength of any kind of electromagnetic radiation always equals the speed of light by dividing the speed of light by either measurement of the frequency or of the wavelength one determines the measurement of the other.
What is wavelength?
- “Radio waves, light waves or infrared (heat) waves are different forms of eke tromagnetic radiation. Each makes a characteristic wave pattern of a particular shape and length as it travels through space. The distance between peaks (high points) is called wavelength. The differences in wavelengths determines different kinds of electromagnetic energy.
- “There is a simple relationship between the frequency of oscillation and wavelength of electromagnetic energy. Wavelength, represented by the Greek lower case lambda (λ), is equal to the speed of light (c) divided by frequency (f).”
- λ = c / f
- f = c / λ
What is amplitude?
- “The strength, or intensity of the wave (analogous to a sound wave's loudness), is known as its amplitude.”
- "What is frequency? Northwestern University.
- Basics of Space Flight - Section I, Jet Propulsion Laboratory, California Institute of Technology, Ch. 6' "Electromagnetic Phenomenon."