Is circuit elements' placement order in a series connection matters?
If we are talking about a pure (spherical) serial circuit (in a vacuum), the order of the components doesn't matter. But if we consider some simple appliance, which is exposed to external world, like, say, a heater with a switch, we can look at the two cases:







simulate this circuit &ndash; Schematic created using CircuitLab

Suppose the R is the heater (or any other load) with exposed body/contacts. Then, the circuit on the left will have these contacts "hot" (I.e. having voltage relative to the ground) even when the switch is open, so one can get electrocuted by touching the exposed part even when off. The circuit on the right doesn't have this problem as R will have zero potential when the switch is off.