Where is constructive interference in a standing wave?

At the crests of the wave and the troughs of the wave.

Constructive interference occurs in a standing wave at specific points called nodes. In a standing wave, two or more waves with the same frequency and amplitude propagate in opposite directions. As a result, they interfere with each other, forming points of constructive and destructive interference.

To visualize the nodes of constructive interference in a standing wave, it's helpful to understand the wave pattern. In a simple harmonic standing wave, such as on a string fixed at both ends or in an organ pipe, there are nodes and antinodes.

Nodes are points on the wave where the displacement of the medium is always zero. These points remain stationary and do not experience any motion. They occur at regular intervals along the wave.

In a standing wave, constructive interference happens at the nodes. At these points, the waves originating from opposite directions meet and have maximum positive displacement. Consequently, the amplitude of the resultant wave at the nodes is greater than the amplitude of the individual waves.

To locate the nodes of a standing wave, you need to know a few key details, such as the wavelength of the wave and the boundary conditions of the medium. Each type of standing wave configuration (e.g., string, tube) has a specific pattern of nodes and antinodes.

By understanding the physics behind standing waves and their formation, you can determine the positions of the nodes and identify where constructive interference occurs within the wave.