Answer
$\lambda=60cm$
Work Step by Step
For the pattern shown, the length of the string is equal to 3 half-wavelengths:
$L = 3(\frac{λ}{2})$
or $\lambda=\frac{2L}{3}$
$L=90 cm=\frac{90}{100}=0.90m$
putting the value of we get
$\lambda=\frac{2(0.90)}{3}$
$\lambda=0.60m$
$\lambda=60cm$
