Energy systems
Energy Systems
Light a LED or sound a buzzer
The flat side of the coin battery is the (+) terminal. To light a LED, the long wire needs to connect with the (+) terminal, and the short wire should has to touch the (—) side. Like a LED, a buzzer is polar – it does not work unless the current is going in the right direction. The red wire has to be attached to the (+) side of the battery and the black wire has to go to the (—) terminal. Either a buzzer or a LED will also work from two AA batteries in series (see Lesson 3), but it is much easier to connect them to coin batteries.