A Level Physics Practice Exam

How does a point on a stationary wave move?

1. In a circular motion

2. In a straight line

3. Up and down around the rest position

4. In a random direction

The correct answer is: Up and down around the rest position

In a stationary wave, also known as a standing wave, the points on the wave exhibit specific motion characteristics due to the nature of their formation. A stationary wave is created by the interference of two waves moving in opposite directions, where some points, called nodes, remain stationary and do not move, while others, called antinodes, experience the maximum displacement. The motion of a point on a stationary wave primarily consists of oscillating up and down around a rest position. This oscillation occurs as the wave propagates, resulting in points along the wave crest rising and falling in a periodic manner. The up and down motion is a direct consequence of the sinusoidal shape of the wave and the superposition principle, which dictates that at certain points along the medium, constructive and destructive interference leads to the described motion. Thus, the correct answer accurately reflects how a point on a stationary wave moves, emphasizing the oscillatory motion about a fixed center or rest position.