Answer:
[tex]\lambda[/tex] = 40 cm
Explanation:
given data
string length = 30 cm
solution
we take here equation of length that is
L = [tex]n \times \frac{1}{4} \lambda[/tex] ...............1
so
total length will be here
[tex]L = \frac{\lambda}{2} + \frac{\lambda}{4}\\[/tex]
[tex]L = \frac{3 \lambda }{4}[/tex]
so [tex]\lambda[/tex] will be
[tex]\lambda = \frac{4L}{3}\\\lambda = \frac{4\times 30}{3}[/tex]
[tex]\lambda[/tex] = 40 cm