A hydrogen atom is in an excited state of principal quantaum number$\; (n)\;$ it emits a photon of wavelength $\;(\lambda)\;,$ when it returns to ground state . The value of n is

Question

$(a)\;\sqrt{\large\frac{\lambda R}{\lambda R-1}}\qquad(b)\;\sqrt{\large\frac{(\lambda R-1)}{\lambda R}}\qquad(c)\;\sqrt{\lambda(R-1)}\qquad(d)\;\sqrt{\large\frac{\lambda R}{\lambda R-1}}$