A string is clamped at both the ends and it is vibrating in its 4th harmonic. The equation of the stationary wave is y=0.3sin0.157xcos200πt . The length of the string is
20 m
80 m
60 m
40 m
In case of 4th harmonic l=4λ2 ⇒2λ=l Put λ = 2πk ⇒4πk = l ⇒l = 4π0.157=80m