A Level Physics Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

Destructive interference occurs when two waves of the same frequency and amplitude meet in such a way that their peaks align with the troughs of one another. This results in them canceling each other out to some degree, leading to a decrease in the overall amplitude of the resultant wave.

In a wave system experiencing destructive interference, the waves typically have a phase difference of 180 degrees (or an odd multiple of π) between them. This cancellation effect can lead to points of zero amplitude, known as nodes, but the primary characteristic denoted by destructive interference is indeed the decrease in amplitude due to the opposing nature of the waves.

This phenomenon contrasts with other effects in wave interference, such as constructive interference, which would increase amplitude, or the formation of standing waves, which can occur as a result of both types of interference depending on the system's boundary conditions.