The equation of a wave is given by y = 2 sin (314t - 2x + π/2)m the wave length of the wave is:

CONCEPT : 

• A progressive wave is one which travels continuously in medium without a change in amplitude and direction and is given by equation is given by

⇒ Y = A Sin(Kx - ωt)

Where A = Amplitude K = Wave vector, t = time and x = distance

• Wave vector is the quantity used to represent the direction of motion and magnitude, which is given by

Where λ = Wavelength 

CALCULATION :

Given y = 2 sin (314t - 2x + π/2)

• The equation of progressive wave is given by

⇒ Y = A Sin(Kx - ωt)

Comparing the given equation to the above equation 

⇒ K = 2 

• The wave vector is given by 

• Hence, option 4 is the answer