Question

A longitudinal wave travels into a medium in which its speed increases. Its wavelength

• A. increases
• B. decreases
• C. remains same
• D. cannot predict

Answer 1

Answer: (A)

increases

The speed of wave is given by
$v=\nu \lambda$
As the frequency of a longitudinal wave is dependent on the frequency of the vibrations that lead to the creation of the longitudinal wave. Therefore, the frequency is always unchanged, irrespective of any changes in speed.
$\Rightarrow v\propto \lambda$
Hence, when a longitudinal wave travels into a medium in which its speed increases, its wavelength also increases.