Based on the equation : $\; \bigtriangleup E = -2.0 \times 10^{-18} J\; (\large\frac{1}{n_{2}^{2}} - \large\frac{1}{n_{1}^{2}})\;$ the wavelength of the light that must be absorbed to excite hydrogen electron from level n=1 to level n=2 will be : $\;(h=6.625 \times 10^{-34} Js\;,C=3 \times 10^{8}\;ms^{-1})$ - Clay6.com, a Free resource for your JEE, AIPMT and Board Exam preparation

Based on the equation : $\; \bigtriangleup E = -2.0 \times 10^{-18} J\; (\large\frac{1}{n_{2}^{2}} - \large\frac{1}{n_{1}^{2}})\;$ the wavelength of the light that must be absorbed to excite hydrogen electron from level n=1 to level n=2 will be : $\;(h=6.625 \times 10^{-34} Js\;,C=3 \times 10^{8}\;ms^{-1})$