Elenco Green Projects - Manual (Page 39)

+
Project #51 Two in Series
Set the switch (S5) to position B, the red
LED (D1) lights and the horn (W1)
sounds. Current flows from the batteries
through the LED and horn back to the
battery through the switch.
The closed switch completes the circuit.
In electronics this is called a closed
circuit. When the switch is set to “C”, the
current can no longer flow back to the
battery, so the LED goes out and the
horn stops making noise. In electronics
this is called an open circuit.
Project #52 Two in Parallel
When you close the switch, both the LED
and horn turn on. Current flows from the
batteries through the LED and horn back
to the battery through the switch.
Remove the horn and notice that the LED
does not change in brightness. In a
parallel circuit, current has more than one
path so removing the horn does not
affect the LED. The voltage is the same
across the LED and horn, but not the
current.
The lights in your home
are wired in parallel so if
one burns out, the others
stay on.
+
-38-
See projects 1 & 3 if you need to recharge the battery (B4).