Physics - Modern Physics Question with Solution | TestHub

The wavelengths of${\text{K}}_{\alpha }$$X$-rays of two metals$\mathrm{A}$and$\mathrm{B}$are$\frac{4}{1875\mathit{R}}$and$\frac{1}{675\mathit{R}}$respectively, where$R$is Rydberg constant. The number of elements lying between$\mathrm{A}$and$\mathrm{B}$according to their atomic numbers is