|The algebraic sum of the currents flowing through a junction is zero. Currents approaching the junction are + while currents going away from the junction are -.|
Kirchhoff's first law when officially stated (see insert at the right) sounds more complicated than it actually is. Generally speaking, it says, the total current entering a junction must equal the total current leaving the junction. After all, no charges can simply disappear or get created, so current can't disappear or be created either. A junction is any place in a circuit where more than two paths come together.
The diagrams below represent several possible circuit junctions and show the currents entering and leaving a junction.
|In this example you will notice that 8 Amps of current enter the junction and 3 and 5 Amps leave the junction. This makes a total of 8 Amps entering and 8 Amps leaving.|
|In this example you will notice 8 Amps and 1 Amp entering the junction and 9 Amps leaving. This makes a total of 9 Amps entering and 9 Amps leaving.|
|In this example you will notice 8 Amps and 1 Amp entering the junction while 7 Amps and 2 Amps leave. This makes a total of 9 Amps entering and 9 Amps leaving.|
©1999 Science Joy Wagon