A Level Physics Practice Exam

What phenomenon occurs at the antinodes of a stationary wave?

1. Destructive interference

2. No movement of particles

3. Maximum displacement occurs

4. Frequency decreases

The correct answer is: Maximum displacement occurs

At the antinodes of a stationary wave, maximum displacement occurs due to constructive interference. In the context of wave behavior, stationary waves are formed by the superposition of two waves traveling in opposite directions, such as waves reflecting off a boundary. At the antinodes, the reinforcement of the waves leads to points where the oscillations of the medium reach their highest values. This means the particles in the medium experience the greatest displacement from their equilibrium position. In contrast, at nodes, there is no displacement because the waves cancel each other out at those points, emphasizing that the antinodes are characterized by significant movement. The phenomenon illustrated at the antinodes is fundamental in understanding wave behavior in systems like strings fixed at both ends or air columns in pipes, where the antinode represents a position of maximum energy oscillation in the wave. Therefore, saying that maximum displacement occurs at the antinodes is a clear and accurate description of the behavior of stationary waves.