The phase difference between two points separated by $\text{0.8} \mathrm{m}$ in a wave of frequency $120 \mathrm{Hz}$ is $0.5\pi$. The wave velocity is

• A

  $\mathrm{144 }\mathrm{m }{\mathrm{s}}^{-1}$
• Correct answer
  B

  $\mathrm{384 }\mathrm{m }{\mathrm{s}}^{-1}$
• C

  $\mathrm{256 }\mathrm{m }{\mathrm{s}}^{-1}$
• D

  $\mathrm{720 }\mathrm{m }{\mathrm{s}}^{-1}$

Hence, the correct answer is option: 'B'.