Q 11-14-142JEE MainJEE Main 2025 (4 Apr, Shift 2)Easy
The displacement of a wave is expressed as $x(t) = 5\cos\left(628t + \dfrac\pi2\right)\ \text{m}$. The wavelength of the wave when its velocity is $300\ \text{m/s}$ is:
Answer: (B) $3\ \text{m}$
$\omega = 628\ \text{rad/s}$, so $f = \dfrac{628}{2\pi} = 100\ \text{Hz}$.
$$\lambda = \frac vf = \frac{300}{100} = 3\ \text{m}$$
Solution by Sreeraj P, M.Sc Physics