How to find the period of fluctuations and wavelength

How to find the period of fluctuations and wavelength

The period and frequency of fluctuations are sizes, the return on the relation to each other. Wavelength is connected with frequency through distribution speed, and cyclic frequency - through the doubled number π.


1. Transfer all basic data to SI units: frequency - in hertz (Hz), cyclic frequency - in radians in a second (the period is glad / c), - in seconds, wavelength - in meters.

2. To find the period of fluctuations, knowing frequency, build it in degree-1 (or that the same, divide number 1 into frequency). If in basic data the cyclic frequency is presented, in the beginning transfer it to usual frequency for what divide on 2π. If in conditions the wavelength is given, before calculation of the period find on it frequency for what divide the speed of distribution of fluctuations into wavelength.

3. For finding of wavelength on frequency divide the speed of distribution of fluctuations into frequency. If in statements of the problem instead of usual frequency it is given cyclic, in the beginning transfer it to usual as it is stated above. If the period is given, at first calculate on it frequency, having built it in degree-1.

4. Speed of distribution of electromagnetic oscillations (including, light) is equal in a vacuum to 299792458 m/s. To learn the speed of distribution of such fluctuations in other environment, divide this constant into the index of refraction of the environment which is dimensionless size. As at air this coefficient is very close to unit, at low requirements to accuracy the equal speed of light can accept the speed of light in air in a vacuum. The sound cannot extend in a vacuum. Its speed in air is 331 m/s, and in water - 1348 m/s. Pay attention: if the speed of light with increase in density of the environment falls, then at a sound it at the same time, on the contrary, increases.

5. Having calculated the period or wavelength, if necessary transfer result to more convenient units: the period - in milliseconds, microseconds, nanoseconds, picoseconds, wavelength - in nanometers, micrometers, millimeters, centimeters, kilometers. It is desirable to carry out the choice of units of measure so that it was not necessary to use an exponential form of record of numbers.

Author: «MirrorInfo» Dream Team