A Level Physics Practice Exam

What are nodes in a stationary wave characterized by?

1. Maximum displacement of particles

2. No movement of particles

3. Constant decrease in amplitude

4. Minimum wavelength

The correct answer is: No movement of particles

Nodes in a stationary wave are characterized by points where there is no movement of particles. In the context of a stationary wave, which is formed by the superposition of two waves traveling in opposite directions, nodes are specific locations along the medium that experience destructive interference. At these points, the amplitude of the wave is effectively zero, meaning that the particles of the medium do not oscillate or move from their equilibrium position. This phenomenon arises because, at a node, the upward displacement of one wave exactly cancels out the downward displacement of the other wave. Therefore, at these points, the energy is focused around the antinodes, where maximum displacement occurs instead. The other options incorrectly describe aspects of the wave motion. The maximum displacement of particles occurs at antinodes, while a constant decrease in amplitude is not a characteristic of a stationary wave; the amplitude remains constant at a node. Lastly, the term minimum wavelength is not relevant to the characteristic of nodes, as nodes relate to displacement rather than to wavelength.