A Level Physics Practice Exam

What describes the impact of a stationary wave on its medium?

1. Particles move freely along the wave

2. Particles oscillate about fixed positions

3. Particles permanently deform under stress

4. Particles travel along the wave to provide energy

The correct answer is: Particles oscillate about fixed positions

The correct understanding of a stationary wave, also known as a standing wave, lies in the nature of its particle motion. In a stationary wave, particles of the medium do not move freely along the wave as they would in a traveling wave. Instead, they oscillate about fixed positions, moving up and down or back and forth but not shifting their overall position through the medium. This oscillation occurs while nodes (points of no displacement) remain stationary, and antinodes (points of maximum displacement) undergo the greatest movement. This oscillation occurs because of the interference of two waves traveling in opposite directions, creating regions where the amplitude is zero (nodes) and regions where the amplitude is at its maximum (antinodes). The particles at the nodes do not move, while those at the antinodes experience the greatest displacement, but all particles return to their original positions after each oscillation. This characteristic differentiates stationary waves from traveling waves, where energy is transmitted along the medium and particles can move significant distances. In contrast, other options misrepresent the behavior of particles in a stationary wave. For example, the idea that particles permanently deform under stress mischaracterizes the temporary nature of oscillation in stationary waves. Additionally, the notion of particles moving freely