Question

Longitudinal waves cannot:

• A. have a unique wave length
• B. have a unique wave velocity
• C. transmit energy
• D. be polarized

Hint:

Polarization is a characteristic property of transverse waves and does not apply to longitudinal waves.

Answer 1

The Correct Option is D

Step 1: Longitudinal waves are waves in which the displacement of the medium is parallel to the direction of wave propagation. Sound waves and waves in springs are examples of longitudinal waves.

Step 2: Unlike transverse waves, longitudinal waves cannot be polarized. Polarization only occurs in transverse waves where oscillations are perpendicular to the direction of propagation.

Step 3: Therefore, the correct answer is that longitudinal waves cannot be polarized.

Answer 2

Longitudinal Waves

Longitudinal waves are waves in which the displacement of the medium is in the same direction as, or the opposite direction to, the direction of propagation of the wave. This is in contrast to transverse waves in which the displacement of the medium is perpendicular to the direction of propagation.

Let's examine the given options:

• (A) have a unique wavelength: Longitudinal waves, like all periodic waves, can have a well-defined wavelength, which is the distance between two successive compressions or rarefactions. So, this statement is false.
• (B) have a unique wave velocity: The velocity of a longitudinal wave in a medium is determined by the elastic properties (e.g., bulk modulus) and the density of the medium. For a given medium under constant conditions, longitudinal waves will have a unique velocity. So, this statement is false.
• (C) transmit energy: Waves, by their nature, are a mechanism for transferring energy through a medium without a net displacement of the medium itself. Longitudinal waves, such as sound waves, certainly transmit energy. So, this statement is false.
• (D) be polarized: Polarization is a property that applies to transverse waves. It describes the orientation of the oscillations in a plane perpendicular to the direction of wave travel. In longitudinal waves, the oscillations are parallel to the direction of wave travel, so there is no orientation of oscillation to define polarization. Therefore, longitudinal waves cannot be polarized. So, this statement is true.

The question asks which of the following longitudinal waves cannot do. Based on our analysis, longitudinal waves cannot be polarized.

Final Answer: (D) be polarized