[pizzaguy541]

I disagree @tiszy

If you put a piece of copper in bulb 7, you're effectively cutting bulbs 3-6 out of the equation entirely. Those light bulbs all have a certain level of resistance (that's why they light up) and the copper replacing bulb 7 should be a lower resistance. Therefore, the electricity would follow that path, bypassing the additional legs of the parallel circuit. Meanwhile, bulbs 1 and 2 would still be in series, meaning that (assuming a 12v system) each bulb would use approximately 6v EACH. We of course making A LOT of assumptions here, things like batt voltage, the bulbs being the same, etc. Obviously if bulb 1 is an LED and bulb2 is incandescent, that changes a bunch of stuff.

Roger_smith has explained it nicely.

This is the correct answer.