Energy of an electron is given by E =-2.178 × 10^-18 J ((Z^2)/(n^2)). Wavelength of light required to excite an electron in an hydrogen atom from…

Energy of an electron is given by $\displaystyle \mathrm{E}=-2.178 \times 10^{-18} \mathrm{~J}\left(\frac{\mathrm{Z}^2}{\mathrm{n}^2}\right)$. Wavelength of light required to excite an electron in an hydrogen atom from level $\displaystyle \mathrm{n}=1$ to $\displaystyle \mathrm{n}=2$ will be : $$\begin{aligned} (\mathrm{h} & =6.62 \times 10^{-34} \mathrm{Js} \text { and } \\ \mathrm{c} & \left.=3.0 \times 10^8 \mathrm{~ms}^{-1}\right) \end{aligned} $$