Question

Please describe how you could quickly determine whether a string of lights is wired in a series or in parallel.

Answer 1

This can be achieved by looking at the lamps, and seeing if their brightness look weak. If they seem to be working on their usual power, then they are wired in parallel. If they seem weak, then they are wired in series. This happens due to the fact that when they are in parallel, for a fixed voltage the total resistance of the circuit decreases. However, if they are in series, the resistance increases, thus reducing the total current and power. This can be seen on the next drawing

The power of each lamp on the first case is

`P=V*I_(lamp)=(V^2)/(R)`

And for the second case

`P=V*I_(lamp)=(((V)/(3))^2)/(R)\text{ = }(V^2)/(9R)`