VISUAL PHYSICS ONLINE

3.1 WAVES

P31 004.m

Diagram 1 shows air particles A, B, C , … M in their equilibrium positions.

Diagram 2 shows their positions at an instant when a longitudinal progressive waves through the air to the right.

In diagram 2, identify two particles which are in phase.

Immediately after this instant of time, in which direction will particle E move?

Identify the particles that are at the centre of the compressions.

Identify the particles that are at the centre of the rarefactions.

If the distance between particles A and D is 10 mm, what is the wavelength of the wave.

How do the motions of the particles in this longitudinal wave differ from the motion of particles in a transverse wave?

View solution below only after you have completed the answering the question.

Solution

1^st step is to identify which particles are in their equilibrium positions.

2^nd step identify those particle that are shifted to the right and those particles that are shifted to the left.

3^rd step identify the compressions C and rarefactions R.

4^th step sketch a sine wave function to represent the horizontal displacements of the particles.

In this longitudinal wave, the particles move parallel to the direction in which the wave is propagating. In a transverse wave, the particles move in a direction perpendicular to the direction in which the wave is travelling.