MCQ
In a simple harmonic wave, minimum distance between particles in same phase always having same speed, is ..........
  • $\lambda / 4$
  • B
    $\lambda / 3$
  • C
    $\lambda / 2$
  • D
    $\lambda$

Answer

Correct option: A.
$\lambda / 4$
a
(a)

$y=A \sin (\omega t-k x)$

$\frac{d y}{d t}=A \omega \cos (\omega t-k x)$

Take $x=0$ and $x=x_1$

$v_1=A \omega \cos (\omega t)$

$v_2=A \omega \cos (\omega t+k x)$

$\left|v_1\right|=\left|v_2\right|$

$|\cos (\omega t)|=|\cos (\omega t+k x)|$

$\therefore k x=\frac{\pi}{2}$

or $x=\frac{\lambda}{4}$

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