Two black boxes display the same impedance at all frequencies. The first contains a single 1 Ohm resistor. Each end is connected to a wire, so that two wires protrude from the box. The second box looks identical from the outside, but inside there are 4 components. A 1 F capacitor is in parallel with a 1 Ohm resistor, and a 1 H inductor is in parallel with the other 1 Ohm resistor. The RC combo is in series with the RL combo, as shown in the figure 

The boxes are painted black, unbreakable, impervious to x-rays, and magnetically shielded.  

[![circuit](https://i.stack.imgur.com/zuORN.png)](https://i.stack.imgur.com/zuORN.png)Demonstrate that the impedance of each box is 1 Ohm at all frequencies.
 What measurement would allow one to determine which box contains the single resistor?