Properties of Standing Waves

What is a standing wave?

• Stationary interference pattern of successive nodes and antinodes

• Created by superposition, when waves travel in opposite directions, they have the same frequency, amplitude, and wavelength

  • Therefore, standing waves have the same wavelength and frequency as the travelling waves that compose them

What is a node?

• Areas of destructive interference

• Points in the medium are at rest

What is an antinode?

• Area of constructive interference

• Points in the medium possess the greatest amplitude

Profile difference between travelling and standing waves

• The profile (shape) of a travelling wave moves along the medium and energy.

• While the profile (shape) of a standing wave does not progress, neither does its energy

Phase difference between travelling and standing waves

• Points along a travelling wave are only in phase when they are a wavelength apart.

• Whereas for a standing wave ALL POINTS between two NODES are in phase pair

Amplitude differences between travelling and standing waves

• All points on a travelling wave will reach the crest or trough at some point in the waves propagation

• While in a standing wave the position is stationary, so some points (the nodes) will always be at a point of rest and other points (antinodes) will oscillate from crests and troughs

What does the velocity of a standing wave refer to?

The velocity refers to the velocity of the travelling waves which compose the standing wave.

What are the 3 types of standing waves?

• closed-closed (nodes at both ends)

• open-closed (one node and one antinode at an end)

• open-open (antinodes at both ends)

What is the fundamental frequency?

• The frequency that produces the simplest standing wave.

• It is also referred to as the first harmonic