Question

Identify the type of sound wave.
A. Electromagnetic wave
B. Longitudinal wave
C. Transverse wave
D. Torsional wave
E. Circular wave

Answer 1

Hint: Sound waves are disturbances in the particles of air which vibrate and due to collisions, the wave will move forward. We will use the direction of motion of particles during vibration and the direction of wave propagation and accordingly we will select the type of wave.

Complete answer:
We are aware that sound waves travel in a conical direction and they require some medium to travel as they cannot be heard in space or on the moon for example where there are no air particles due to lack of any atmosphere surrounding it. We also know that they travel due to collisions between adjacent particles and thus have a faster speed in denser states of matter i.e. they generally travel faster in solids as compared to fluids and faster in liquids than in gases. This must mean that the particles must vibrate in the same direction as the direction of propagation of a sound wave. These all properties hint towards the sound wave being a Longitudinal wave. For longitudinal waves the particles do not move along the path but just oscillate in the same direction as the direction of propagation of the wave about a mean position. This type of wave can be observed in a slinky by compressing a region of the spring and then releasing it. It appears as if the compression is moving but the coils making up the compression don’t.

So, the correct answer is “Option B”.

Note:
Although on a graph we draw sound waves as a transverse sine wave, that denotes either the pressure in the region on the wave or the density of particles in that region which changes due to movement of particles about their mean positions.