Question

A plane wave is represented by

$x=1.2sin(314t+12.56y)$

Where x and y are distances measured along in x and y direction in meters and t is time in seconds. This wave has

[MP PET 1991]

• A. A wavelength of 0.25 m and travels in + ve x direction
• B. A wavelength of 0.25 m and travels in + ve y direction
• C. A wavelength of 0.5 m and travels in - ve y direction
• D. A wavelength of 0.5 m and travels in - ve x direction

Answer 1

The correct option is C

A wavelength of 0.5 m and travels in - ve y direction

The given equation representing a wave travelling along -y direction

(because '+' sign is given between t term and x term).

On camoaring it with $x=Asin(\omega t+ky)$

We get $k=\frac{2\pi }{\lambda }=12.56\Rightarrow \lambda =\frac{2\times 3.14}{12.56}=0.5m$