BBC Bitesize - GCSE Physics (Single Science) - Properties of waves - AQA - Revision 2
the significance of wavelength. Learn the relationship of wavelength, frequency , and wave speed, and how Wavelength equation with Greek letter lambda. The relationship between the speed of sound, its frequency, and wavelength is . Note that you can also easily rearrange the same formula to find frequency or. The time period of a wave can be calculated using the equation: Question. What is the speed of a wave with a frequency of Hz and a wavelength of 25 m ?.
The analysis of the wave can be based upon comparison of the local wavelength with the local water depth. The figure at right shows an example. As the wave slows down, the wavelength gets shorter and the amplitude increases; after a place of maximum response, the short wavelength is associated with a high loss and the wave dies out. The analysis of differential equations of such systems is often done approximately, using the WKB method also known as the Liouville—Green method.
The method integrates phase through space using a local wavenumberwhich can be interpreted as indicating a "local wavelength" of the solution as a function of time and space. In addition, the method computes a slowly changing amplitude to satisfy other constraints of the equations or of the physical system, such as for conservation of energy in the wave.
Properties of waves
Crystals[ edit ] A wave on a line of atoms can be interpreted according to a variety of wavelengths. Waves in crystalline solids are not continuous, because they are composed of vibrations of discrete particles arranged in a regular lattice.
This produces aliasing because the same vibration can be considered to have a variety of different wavelengths, as shown in the figure.
The range of wavelengths sufficient to provide a description of all possible waves in a crystalline medium corresponds to the wave vectors confined to the Brillouin zone.How To Calculate The Energy of a Photon Given Frequency & Wavelength in nm Chemistry
It is mathematically equivalent to the aliasing of a signal that is sampled at discrete intervals. The density amplitude is the maximum change in density.
Intensity – The Physics Hypertextbook
Measuring displacement might as well be impossible. For typical sound waves, the maximum displacement of the molecules in the air is only a hundred or a thousand times larger than the molecules themselves — and what technologies are there for tracking individual molecules anyway? The velocity and acceleration changes caused by a sound wave are equally hard to measure in the particles that make up the medium.
Density fluctuations are minuscule and short lived.
The period of a sound wave is typically measured in milliseconds. There are some optical techniques that make it possible to image the intense compressions are rarefactions associated with shock waves in air, but these are not the kinds of sounds we deal with in our everyday lives.
Pressure fluctuations caused by sound waves are much easier to measure.
Animals including humans have been doing it for several hundred million years with devices called ears. Humans have also been doing it electromechanically for about a hundred years with devices called microphones.
All types of amplitudes are equally valid for describing sound waves mathematically, but pressure amplitudes are the one we humans have the closest connection to.
In any case, the results of such measurements are rarely ever reported. Instead, amplitude measurements are almost always used as the raw data in some computation. When done by an electronic circuit like the circuits in a telephone that connect to a microphone the resulting value is called intensity. When done by a neuronal circuit like the circuits in your brain that connect to your ears the resulting sensation is called loudness.