Standing waves

Principle

When the sound wave of a sound propagates in air, this wave causes all of the air particles that it reaches to oscillate. If the sound is generated continuously, all of the particles are constantly in motion. In this experiment, the students observe the generation of standing waves in a glass tube at certain frequencies. They measure the positions of the nodes and antinodes. In the evaluation part, they work out the conditions for the natural frequencies of a hollow body.

Benefits

• Experiment is part of an experiment set with a total of 22 experiments about generation, propagation and perception of sound, oscillations and waves
• Particularly appropriate as an experiment for first contact with physics in general
• With graphic student worksheets
• With detailed instructor information
• Optimized for tight schedules, i.e. minimum preparation time required

Tasks

During this experiment, examine how there can be places in a hollow body where no sound can be heard in spite of a continuous generation of sound. A case like this, when the air particles obviously do no longer oscillate in some places, i.e. when they "stand", is also referred to as a standing wave. Observe the sound propagation without a hollow body. Produce a standing wave in a hollow body (glass tube). Examine the conditions under which standing waves occur.

Learning objectives

• Standing waves
• Node
• Antinode
• Natural frequency
• Hollow body