Figure 1 indicates that the light reading dropped irrevocably during the recording. So, the question is:

Which socket was the light plugged into?

Figure 2 shows a comparison of the current and light readings. Current 2 is indicated in dark gray. Current 4 is indicated in a lighter gray. Light is indicated in yellow. Current 2 and 4 shows activity after the first quarter of the recording, indicating that something was plugged into both sockets during the middle part of the recording. Current 1 and 3 were at zero, indicating that nothing was plugged into them. The light reading indicates that a light went out before current reached either plug 2 or 4, leading me to the following conclusion:

The light that went out was not plugged into the Plug.

Figure 3 shows the first 50 samples of light (yellow) and voltage (gray), indicating that the light oscillating twice as fast as the voltage and that light is slightly behind in phase. This is evidence that the light has the same voltage source as the plug.

Figure 4 an aliasing pattern found while sampling the voltage. (voltage in black, light in red, microphone in gray)