Standing waves can be created by both an incoming wave and its reflection as well as by two waves of the same frequency traveling in opposite directions. In fact, standing waves are often produced in systems where waves interfere constructively and destructively.
When an incoming wave meets a boundary, such as a fixed end or a reflected surface, it undergoes reflection. The reflected wave then combines with the incoming wave, leading to interference. If the incoming and reflected waves have the right conditions, such as specific wavelengths or frequencies, they can interfere to create a standing wave pattern. This pattern consists of nodes (points of no displacement) and antinodes (points of maximum displacement) that appear to be stationary. Musical instruments like guitars and organs produce sound using this principle, where the strings or pipes create standing waves through reflection and interference.
Similarly, standing waves can also be generated by two waves traveling in opposite directions. This occurs when two waves of the same frequency and amplitude travel through the same medium in opposite directions and interfere with each other. The points of constructive interference become the nodes, and the points of destructive interference become the antinodes, creating a stationary pattern. This phenomenon is commonly observed in physics demonstrations using a rope or a stretched string. By vibrating the ends of the rope or string with the same frequency and amplitude, standing waves are formed due to the interference of the two waves traveling in opposite directions.
In both cases, the key aspect is the interference of waves that leads to stationary patterns. Whether it's through reflection and interference with an incoming wave or the interference of waves traveling in opposite directions, standing waves can be formed and exhibit distinct node and antinode patterns.