A Level Physics Practice Exam

What kind of wave is formed by two waves of equal frequency travelling in opposite directions in a medium?

1. A traveling wave

2. A stationary wave

3. A longitudinal wave

4. A surface wave

The correct answer is: A stationary wave

When two waves of equal frequency travel in opposite directions within the same medium, they can interfere with each other to create a stationary wave, also known as a standing wave. This phenomenon occurs because the waves will superimpose, meaning their amplitudes add together in certain points (antinodes) and cancel each other out in other points (nodes). This results in specific points along the medium that remain fixed (nodes), while others vibrate with maximum amplitude (antinodes). The stationary wave pattern is characterized by these fixed points and the regular oscillation of the medium at the points of maximum amplitude. In contrast, a traveling wave moves through the medium and does not create stationary points. Longitudinal and surface waves refer to the type of motion involved in the wave and do not specifically describe the effect of two opposing waves creating a stationary pattern. Thus, the correct answer highlights the phenomenon of interference that leads to a standing wave characteristic.