Reply to "series versus parallel wiring for lights"

Resistances in series are known as a voltage divider. With light 1 and light 2 you have added two resistances together resulting in more voltage drop (R1 + R2 = Rtotal).  Add in light three (Resistance 3) and there is not enough voltage to light the element, but current can pass to complete the circuit and keep lights 1 and 2 illuminated, but dimmer (less voltage).  Put them in // and the voltage across each resistance remains the same.  The series equation is as follows:  V1 = (R1/(R1+R2))*V where V1 is the voltage across light 1, V is the source voltage.  V2 is similar in that V2 = (R2/(R1+R2))*V.