Simple circuits and the direction of batteries

[kjamha]

When constructing a simple circuit with a battery, bulb and a switch, the placement of the battery is unimportant (I can hook up the battery + then - or - then +). So why is it that so many battery powered electronic devices only work if the batteries are inserted in a specific direction?

 

[cjl]

Because many devices care about polarity. If you want to see this in your simple circuit, replace the bulb with an appropriate LED.

 

[Drakkith]

As Cjl said, there are electronic components that care a great deal about polarity. Transistors and diodes are two examples. Reverse the polarity and neither of these components will function correctly and may actually be destroyed.

 

[sophiecentaur]

Then there are electric motors, many of which go one way with one connection and the other way when connected the other way. That is pretty relevant!
Swap the connections to an electromagnet and the N pole becomes an S pole.