Wave Interference and Standing Waves Practice Test

Two identical loudspeakers emit coherent sound waves in phase. A listener stands where the path-length difference from the speakers is $\Delta L=1.5\lambda$. Assuming equal amplitudes, which interference is produced at the listener’s location?

A string of length $1.20,\text{m}$ is fixed at both ends and driven at a frequency that produces the standing-wave pattern shown. Points $N_1$, $N_2$, and $N_3$ are labeled as nodes, and points $A_1$ and $A_2$ are labeled as antinodes. The string’s shape oscillates in time, but the node locations remain fixed. Which statement correctly describes the motion at a node compared with an antinode?