Consider a hypothitical hydrogen -like atom . The wavelength in A for spectrical lines for transitions from n=P to n=1 are given by $\;\lambda=\large\frac{1500P^2}{P^2-1}\;$ where P=2 , 3 ,4,----. Then wavelength of least energetic and most energetic photons in this series .

Question

$(a)\;2000A^{0}\qquad(b)\;3000A^{0}\qquad(c)\;4000A^{0}\qquad(d)\;5000A^{0}$