Step 1: Analyzing the graph.
From the given \( I-V \) diagram, we observe that the power increases with the voltage initially and then decreases. Therefore, \( P_2<P_1 \).
Step 2: Conclusion.
The correct relationship between \( P_1 \) and \( P_2 \) is \( P_2<P_1 \), which corresponds to option (2).