Answer
$\lambda=10cm$
Work Step by Step
We know that,
$v=f\lambda$
This can be rearranged as:
$\lambda=\frac{v}{f}$..............eq(1)
Then, we find the period:
$T=2(0.50)=1s$
The value of the period can be used to find the frequency:
$f=\frac{1}{T}=\frac{1}{1}=1Hz$
We plug in the known values in eq(1) to obtain:
$\lambda=\frac{10\frac{cm}{s}}{1}=10cm$
