Standing wave


When the next wave and the reflected waves create two waves propagating in the same way but in the opposite direction, they interfere with each other and form a node (the point is not oscillating) and abdomen (are the polar oscillation amplitude long). The phenomenon is called standing wave. The distance between two adjacent belly button or two by half a wavelength.

Based on the characteristics of the waves allows us to measure λ stop correctly and easily. We can determine the velocity v is the wavelength λ knowing and frequency f ....

Standing wave phenomena on the wire

Get a plastic rope, about 2m long, tie one end fixed to the weights and weights squeezed through a horizontal iron bar. The other end is oscillating by a vibrator (picture below).

Gradual change of machine vibration (ie changes the oscillation frequency of the line connected to the machine), to a time when we see the string vibrates with a stable image which places very strong vibration, and the almost no vibration place (Figure below).

The phenomenon can be explained as follows. Ranging from machine vibration transmitted from one end of the string to the top end of the rope, as a transverse wave. By the end of the rope, the reflected waves and transmitted back to the line connected to the vibrator. Waves and reflected waves to satisfy conditions combined wave. Here the end of the rope does not fluctuate, meaning reflected waves and wave to each other in opposite phase it. The result is on the ropes with the interference of two waves combined with different frequency and phase tdaydieemr opposite end of the rope (can be considered the next wave generation source (the line) and the source of reflected waves (Post Wire) combined two wave sources).

Conclusion

Waves have belly buttons and fixed in space called coherence. Note that there are two components wave travels in the other two-way combination of two waves nhau.Su This gives images such coherence.

Standing wave phenomenon allows us to see with the naked eye specific wavelength λ λ and measured accurately. For sound waves and other types of waves, the measured frequency f is also simple. Between velocity v, f wave frequency and wavelength λ, with λ relation v = f. So stop wave phenomena also provides a simple method determined by measuring λ v and f.


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