Question

The equation of a wave travelling in a string can be written as $y=3\cos \pi (100t-x)$. Its wavelength is $(y$ in $cm$ )

• A. 3 cm
• B. 10 cm
• C. 2 cm
• D. 5 cm

Answer 1

Answer: (C)

$y=3\cos \pi (10,t-x)=3\cos (100\pi t-\pi x)$
Comparing it with $y=a\cos \left(\frac{2\pi }{T}t-\frac{2\pi }{\lambda }x\right)$, we get
$\frac{2\pi }{\lambda }=\pi$ or $\lambda =2cm$