Question

The equation of a wave is $y=3\cos \pi (100t-x)$ where $y$ and $x$ are in $cm$ and (in second). The wavelength of this wave is:

• A. 100 cm
• B. 5 cm
• C. 3 cm
• D. 2 cm

Answer 1

Answer: (D)

The equation is given $y=3\cos \pi (100t-x)$...(1)
The standard equation of wave is
$y=a\cos \left(\omega t-\frac{2\pi }{\lambda }x\right)$..(2)
Comparing the given equation (1) to standard equation (2)
we get $\frac{2\pi }{\lambda }=\pi$
or $\lambda =2cm$