Step 1: Understanding the Concept:
Energy of hydrogen-like atom: \(E = -\frac{13.6 Z^2}{n^2}\) eV. For H, \(Z=1\); for He\(^+\), \(Z=2\).
Step 2: Detailed Explanation:
\(E_n(\text{H}) = -\frac{13.6 \times 1^2}{n^2}\).
\(E_n(\text{He}^+) = -\frac{13.6 \times 2^2}{n^2} = -\frac{13.6 \times 4}{n^2} = 4 \times E_n(\text{H})\).
Step 3: Final Answer:
Thus, energy = \(4E_n\).