A Level Physics Practice Exam

How does a particle on a stationary wave move?

1. Moves in a straight path

2. Oscillates around the equilibrium position

3. Moves indefinitely without oscillation

4. Falls to the lowest point of the wave

The correct answer is: Oscillates around the equilibrium position

In the context of stationary waves, the movement of a particle on the wave is characterized by oscillation around a fixed equilibrium position. A stationary wave, also known as a standing wave, does not propagate energy through space like a traveling wave. Instead, it is formed by the interference of two waves traveling in opposite directions, leading to regions of constructive and destructive interference. In these stationary waves, certain points, known as nodes, remain fixed while other points, known as antinodes, exhibit the maximum displacement. The particles at the antinodes oscillate back and forth, moving from a maximum positive displacement to a maximum negative displacement, and they do this around the equilibrium position. This oscillation occurs due to the restoring forces acting on the particles, bringing them back to equilibrium after being displaced. This behavior is fundamental to understanding how energy is stored and transferred in waves. While other choices suggest continuous movement or falling to a point, the actual dynamics of particles in a stationary wave are limited to oscillation about fixed points, which is accurately described by the correct answer.