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14. waves and sound — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysics14. waves and sound1 Mark
MCQ
$y = a\cos (kx + \omega t)$ superimposes on another wave giving a stationary wave having node at $x = 0.$ What is the equation of the other wave
  • A
    $ - a\cos (kx + \omega t)$
  • B
    $a\cos (kx - \omega t)$
  • ✓
    $ - a\cos (kx - \omega t)$
  • D
    $ - a\sin (kx + \omega t)$
✓

Answer

Correct option: C.
$ - a\cos (kx - \omega t)$
c
(c) $a\cos (kx + \omega \,t)$
hence ${y_{{\rm{reflected}}}} = a\cos ( - kx + \omega \,t + \pi ) = - a\cos (kx - \omega \,t)$

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