Mechanical wave – the process of distribution of fluctuations in an elastic medium accompanied with transmission of energy of the fluctuating body from one point in an elastic medium to another. Important characteristics of a wave: length and phase speed.
It is required to you
- - calculator.
Instruction
1. Speed of a wave and its length are interconnected. Wavelength it is considered to be distance which point with a constant phase during the period of fluctuation of T.V to physics will pass this size designate by a letter λ.
2. Before starting calculation of speed and wavelength, transfer all initial sizes presented in the conditions of a task to the SI system. That is the speed of a wave will be calculated in meters per second, frequency – in hertz, length of waves – in meters, and cyclic frequency – in radians in a second.
3. Wavelength is determined by a formula λ = by vT in which v is its phase speed. Besides, wavelength can be found, having divided the speed of light into wave frequency. So, length of a radio wave is: 300000000/1500000 = 200 meters.
4. Thus, the more value of frequency of a wave, the less its length. Waves are ultrashort (from 0.1 to 10 meters), short (from ten to hundred meters), averages (100-1000 meters) and long (length exceeds 1000 meters and can reach 10000 meters).
5. The period of a wave can be written down through its frequency. This relation is written down as follows: T = 1/f where f is an indicator of circular frequency.
6. In the dispersing environment such concept as group speed is used. This indicator is calculated by a formula Vgr = by dw/dk in which k is wave number, and w is circular frequency.