Wavelength and Frequency

(n) $\lambda =5$ $$

$$ $(\mathrm{n},\mathrm{m})$  : Integers

$\begin{array}{rr}& \left(\frac{2m+1}{2}\right)\lambda =\frac{3}{2}\\ & \Rightarrow \mathrm{}\frac{3/2}{5}=\frac{2m+1}{2n}\\ & \Rightarrow \mathrm{}3n=10m+5\end{array}$

$$ $\mathrm{N},\mathrm{m}$  are integers.

So, $\mathrm{m}=1,\mathrm{}\mathrm{n}=5,\mathrm{}\lambda =1$ $\mathrm{}\mathrm{}$

$\begin{array}{lll}\mathrm{m}=4& \mathrm{n}=15& \lambda =\frac{1}{3}\\ \mathrm{m}=7& \mathrm{n}=25& \lambda =\frac{1}{5}\end{array}$