Circuit Fundamentals
in series or parallel.
A simple series circuit is shown oposite, consisting of a cell (battery) and two lamps.
As electrons pass around a circuit, they lose energy.
(Electrons are not "used up" in any way. Indeed, if they were, then the whole circuit would become radioactive!!)
This means that in a series circuit the current will be the same where ever it is measured.
If three ammeters were placed in the series circuit as shown below, they would all have the same reading.
Electrons cannot give out any more energy in a circuit than they are supplied with initially by the power supply or battery.
In a simple series circuit this means that the sum of the voltages across all of the components is equal to the voltage of the power supply.
Therefore in the series lamp circuit;
voltage across lamp 1 + voltage across lamp 2 = voltage of battery, V.
A simple parallel circuit is shown oposite, consisting of a cell (battery) and two lamps.
Each lamp is connected directly (through an ammeter) to the battery, and
therefore the voltage across each lamp is the same as the battery voltage.
However, the current is split at each junction. This means that: I = I1 + I2
