1. The Parallel Circuit Total Resistance Kirchoff’s Current Law

2. Parallel Circuits

3. The Parallel Circuit
Two or more resistors provide a separate current path, and are connected across the same voltage source
Current : ITotal = I1 + I2 + I3 …
Voltage : VS = V1 = V2 = V3 ….

4. Parallel Resistance
When connected in parallel, total circuit resistance decreases.
Total resistance will be smaller than the smallest resistor.

5. Parallel Resistance For three or more resistors: For two resistors:
1/RT = 1/R1 + 1/R2 + 1/R
1/R1 + 1/R2 + 1/R 1
RT =
RT =
R1 x R2
R1 + R2

6. Kirchoff’s Current Law
The algebraic sum of all the currents entering and leaving a junction is equal to zero.
ITotal + I1 + I2 + I3 … = 0
e.g., = 0
If you consider the direction of the inward current at a junction as positive, then the outward current at that junction will have a negative direction.
ITotal I1 I2 I3

7. Kirchoff’s Current Law
The total circuit current (IT) entering a junction is equal to the sum of the currents leaving that junction.
ITotal = I1 + I2 + I3 …
e.g., =
ITotal I1 I2 I3